This document contains implementation examples and techniques using Linksys, Inc.
and, in some instances, other company’s technology and products and is a
recommendation only and does not constitute any legal arrangement between Linksys,
Inc. and the reader, either written or implied. The conclusions reached and
recommendations and statements made are based on generic network, service and
application requirements and should be regarded as a guide to assist you in forming your
own opinions and decision regarding your particular situation. As well, Linksys reserves
the right to change the features and functionalities for products described in this
document at any time. These changes may involve changes to the described solutions
over time.
Use of Proprietary Information and Copyright Notice:
This document contains proprietary information that is to be used only by Linksys
customers. Any unauthorized disclosure, copying, distribution, or use of this information
is prohibited.
Please Note:
Design and specifications are subject to change without notice.
Navigating the SPA941 GUI......................................................................................................................13
Definitions for the Four Call Appearances.............................................................................................14
4CALL FEATURES ..............................................................................................................................15
Selecting Audio I/O Device and Line.......................................................................................................15
Making Calls ..............................................................................................................................................16
Hold and Resume......................................................................................................................................17
User Interface .........................................................................................................................................23
Service Provider Requirements..............................................................................................................24
5MEMORY FEATURES AND OTHER USER ACCESSIBLE SETTINGS...........................................25
Personal Directory....................................................................................................................................26
Entering and Saving Settings..................................................................................................................27
Reboot and Restart...................................................................................................................................31
Ring Tone...................................................................................................................................................32
Star Code to Activate/Deactivate Certain Services...............................................................................33
Data Types.................................................................................................................................................45
System Parameters...................................................................................................................................51
System Configuration ..........................................................................................................................51
User Parameters........................................................................................................................................74
Info Parameters (Read Only)....................................................................................................................75
This Administration Guide provides instructions on managing and operating the SPA941 IP Telephone.
The Guide covers the following topics:
• General Operating Information
• Call, Voice, Signaling Features, and Hardware Functionality Descriptions
• Configuration, Performance, and Troubleshooting Guidelines
• Provisioning
The SPA941 User Guide provides more details on how to use the phone’s features via the phone’s
physical interfaces, including the softkeys, display menus, the key pad, and dedicated buttons. The
Administrative Guide is helpful for network administrators that need detailed information on how to
configure the phone from the phone’s Web Server, or need access to the phone’s troubleshooting and
performance functions. Finally, the document also covers provisioning of the SPA941.
• Important Operating Information
Please insure the safe operation of the SPA941 by following the operating instructions in this section.
Compliance and Safety Information
This equipment has been tested and found to comply with the limits for a Class B digital device in
accordance with the specifications in part 15 of the FCC rules. This product bears the CE Marking
indicating compliance with the 89/336/EEC directive. Standards to which conformity is Declared: EN
61000-4-2:1995, EN 61000-4-3:1997, EN 61000-4-4:1995, EN 61000-4-5:1995, EN 61000-4-6:1996, EN
61000-4-8:1994, EN 61000-4-11:1994, EN 61000-3-2:2001, EN 61000-3-3:1995 & EN 55022:1998 Class
B Modifications to this product not authorized by Linksys could void FCC approval, thereby terminating
end user authority to use this product.
For indoor use only.
Read installation instructions before connecting to a power source. The electric plug and socket must be
accessible at all times as this is the main method to disconnect power from the device.
Shock Hazard:
Do not operate near water or similar fluid.
Do not work with this device during periods of lightning activity.
Do not touch wires at the end of cables or within sockets.
One Year Limited Hardware Warranty
Linksys provides a one (1) year limited hardware warranty. Linksys warrants to customer that this product
will conform to its published specifications and will be free from defects in material and
workmanship at the time of delivery and for a period of one year thereafter. Without limiting the
foregoing, this warranty does not cover any defect resulting from (i) any design or specification sup plied
by an entity other than Linksys, (ii) non-observance of technical operating parameters (e.g., exceeding
limiting values), or (iii) misuse, abuse, abnormal conditions or alteration by anyone other than Linksys.
Replacement, Repair, Refund:
After the receipt of an RMA (Return Materials Authorization) request, Linksys will attempt to refund, repair
or replace this device. To receive an RMA number for this device, contact the party from whom it.
This unit may have been supplied by or sponsored by a telephone service provider. If so, the service
provider or network administrator who supplied the unit may have provided a pre-configuration of the
network and service settings. Depending on the configuration policy, end user access to the local
configuration settings may be restricted or inaccessible. Therefore, some of the network and service
configuration setting instructions described in the following sections may not be available on all units.
• SPA941 Overview
The SPA941 is a SIP based IP telephone offered by Linksys, a division of Cisco Systems. The SPA941
supports up to four phones lines of operation. It has a pixel-based display and a graphical user interface
that provides access to the phone’s functions and features. Figure 1.1 shows an illustration of the phone.
• Five volt DC Universal (100-240 Volt) Switching Power Adapter
• LED Test Function
SPA941 Features and Functions
•Up to Four Call Appearances with Independent Configuration and Registration
The SPA941 ships with two line appearances enabled. A two line upgrade is available via a
software license key installed locally using the SPA941 web interface, or installed remotely
via a secure profile update.
• Call Number using Name - Directory Matching, Log Matching, or via Caller ID
• Subsequent Incoming Calls with Calling Name and Number
• URI (IP) Dialing Support (Vanity Numbers)
• Configurable Dial Plans with Auto-Completion of dialed number
• Do Not Disturb (callers hear line busy tone)
• On Hook Default Audio Configuration (Speakerphone and Headset)
• Multiple Ring Tones with Selectable Ring Tone per Extension
• Date and Time with Intelligent Daylight Savings Support
• Call Timer
• Call Duration and Start Time Stored in Call Logs
• Name and Identity (Text) Displayed at Start Up
• Distinctive Ringing Based on Calling and Called Number
• Ten User Downloadable Ring Tones - Ring Tone Generator Free from www.linksys.com
• Speed Dialing
• Configurable Dial/Numbering Plan Support - per Line
• DNS SRV and Multiple A Records for Proxy Lookup and Proxy Redundancy
• Syslog, Debug, Report Generation, and Event Logging
• SecureCall Encrypted Voice Communication Support
• Built-in Web Server for Administration and Configuration with Multiple Security Levels
• Automated Provisioning, Multiple Methods. Up to 256 Bit Encryption: (HTTP, HTTPS, TFTP)
• Optionally Require Admin Password to Reset Unit to factory Defaults
** Feature requires support by call server
Navigating the SPA941 Graphical User Interface
Note: Although this guide provides an overview of how to navigate the SPA941 Graphical User Interface
(GUI), its primary focus is to describe the administrative functions available via the phone’s web interface.
For more detailed discussion of the phone’s user interface, please refer to the SPA941 User Guide.
The user can invoke the phone’s GUI by pressing the menu button, and can navigate through the menus
using the round directional rocker knob and the soft keys. The menus are hierarchical. The select soft
key appears when a menu entry has a sub-menu. The sub-menu is entered by pressing the select soft
key, and exited by pressing the cancel soft key. The menus can be exited, and the phone returned to it
default display, by pressing the menu button.
The phone has four soft keys, but at times, more than four functions can be performed with the soft keys.
When this occurs, a small triangle appears at either the bottom right or the bottom left corner of the
display. This indicates that more soft key functions can be accessed by pushing the four way rocker knob
right or left respectively.
Up to four menu items can be displayed at one time. The entries in each menu can be cycled through in
a circular fashion by pressing the up and down arrows on the directional rocker knob. Pressing the down
arrow when the last entry in a menu is selected causes the cursor to move back to the top entry in the
menu list. Press the up arrow when the first menu entry is selected causes the cursor to move to the last
entry in menu.
While the user is navigating the menus down to a leaf level item, a number is displayed on the left side of
each menu entry that indicates its position in the current menu list. A menu item can be directly accessed
by typing its number on the keypad, even if the item isn’t currently visible on the display. For instance,
when the menu key is pressed to display the top level menus, items one through four are displayed. Item
nine can be immediately entered by pressing the 9 key on the keypad, without having to scroll down to
that item. Similarly, the fifteenth item in a menu can be entered by pressing the 1 key followed by the 5
key, with less than a two second pause between the key presses. Any leading 0 entries are ignored.
Some of the entries in the menus, such as those in the Status menu, are only informational; these entries
cannot be changed from within the menus. Typically only the cancel soft key is active when informational
menu entries are displayed.
The changeable menu entries can be modified by pressing the select soft key while the entry is
highlighted. The soft keys change to display the list of choices to modify the selected phone feature, such
as add, paste, edit, and delete. The modified entry can be saved by pressing the save soft key, or
discarded by pressing the cancel soft key.
A menu item’s display string may be wider than what can be displayed. When the user highlights a wide
item, the SPA941 automatically scrolls the contents horizontally from right to left so that the user can view
the entire text string.
Definitions for the Four Call Appearances
Some definitions:
•Station: A SPA941 phone (or a similar device in the Linksys SPA family) with one or more
Extensions and Call appearances provisioned
•Ext: An extension in the SPA941 is a VoIP account in a voice service provider (VSP)’s network or
an IP-PBX system. An extension can be uniquely identified with a User ID (like a phone number)
that is unique within the VSP. Up to 4 extensions can be configured in the SPA941, which are
refered to as Ext 1, Ext 2, Ext 3, and Ext 4 (or simply E1, E2, E3, and E4 respectively). Note that
the same extension can be configured on more than one station. These extensions are called
Shared Extensions. Extension 1 is referred to as the Primary Extension. Some features can only
be activated on the Primary Extension, such as Call Forwarding and Voice Mail Waiting Indicator
(VMWI).
•Call Appearance: Physically a call appearance corresponds to a Line Key on a station. There are
four Line Keys on the SPA941, which are referred to as Line Keys 1, 2, 3, and 4, or, L1, L2, L3,
and L4 respectively). Functionally, a call appearance is an instance of an extension. If an
extension is assigned to Line Keys on multiple stations, it is a Shared Line Appearance. One
extension can be assigned to multiple Line Keys on a SPA941. In fact, all four call appearances
can be instances of the same extension. (This extension is not a Shared Line Appearance
unless it is also assigned to a Line Key on another station.) Any of the four Line Keys can be
disabled. Each call appearance supports one call at a time, either active or on hold.
•VoIP Interface (VI): An Extension and its associated control parameters configured on a particular
station. The SPA941 includes a rich set of configuration parameters to control the operation
when calling via the account. Configuring an extension on the SPA941 includes configuring the
core account information and the set of VI control parameters. While the account information is
usually the same for a shared extension on different stations, the rest of the VI parameters can be
different. For example, the dial plan or the preferred codec to use when making a call on this
extension could be different for two different stations sharing the extension.
•Call Appearance State (CAST): The state of a call appearance which can be one of the following:
o Disabled: The Line Key is disabled
o Idle (Ready): The Call Appearance is ready for use
o Dialing: Collecting digits from the user to be dialed out from this Line
o Calling: Waiting for the called party to respond
o Proceeding (a.k.a. Progressing): Called party’s station is ringing
o Ringing (a.k.a. Alerting): Incoming call, station is ringing
o Connected: Connected with remote party
o Held: Remote party is on hold
o Invalid: Remote party hangs up or error while attempting outbound call
o Busy: the line is being used by another station (shared line only)
•Call State: A Call Appearance State followed by the term “Call”. For example, a Ringing Call, a
Dialing Call
•Active (Call) State: If the state is Dialing, Calling, Proceeding, Connected, or Invalid. When the
state of the Call is Active, it is referred to as an Active Call
•Standby (Call) State: the state is Ringing or Holding. When the state of the Call is Standby, it is
referred to as a Standby Call
•Key: Any one of the keys on the SPA941 keypad. A Key has two states: down (when pressed),
and up (when released)
•Button – a Key with an on and off state. The on/off state toggles when the key is pressed down
where applicable. There are 3 buttons on the SPA941: SPEAKER, HEADSET, and MUTE. Each
button has an associated LED that indicates the on/off state.
• SK(label) – Soft key with the given label, such as SK(select), SK(cancel), SK(dial), SK(conf),
SK(xfer)
• Call Features
Selecting Audio I/O Device and Line
There are three sets of audio I/O devices available: a) Handset, b) Built-in microphone and speaker, and
c) External microphone and headset. The speaker is also used for ri nging. For convenience, where the
context is clear, these are referred to as (b) the speaker, and (c) the headset.
Only one audio device can be selected at anytime. The speaker is selected by pressing the SPEAKER
button. The headset is selected by pressing the HEADSET button. When the SPEAKER or HEADSET is
selected, the corresponding LED will be steady GREEN. The handset is selected whenever it goes from the on-hook to the off-hook position. Hence selecting or turning on of any of the audio device is equivalent
to an off-hook action, while turning off of any of the audio devices while it is equivalent to an on-hook
(hang-up) operation.
When there are no active calls, all audio devices are deselected. When any one of the calls becomes
active, the handset will be selected automatically as the audio device if it is off-hook, else the speaker or
the headset will be selected according to configuration: the user can configure whether speaker or the
headset device has higher preference.
A line is selected by pressing the corresponding Line Key.
To make or receive calls, the user must select a call appearance (Line Key) or an audio device. If the
user selects a call appearance, then an audio device is selected automatically according to user’ s
preference setting. If the user selects an audio device, an idle call appea rance is selected automatically
in the order L1, L2, L3, and L4. The user may switch between audio devices while the call in any of the
active states.
Exception: When a new call appearance is selected automatically when the user presses the conf soft
key or the xfer soft key, the SPA941 will attempt to pick an idle call appearance that is on the same
Extension as the last active call. If that call appearance is not available, the SPA941 attempts to pick one
whose Extension has the same Proxy server as the last active call. Finally, if that fails, the first idle call
appearance is selected, in the order L1, L2, L3, L4.
Making Calls
There are two steps in making a call:
1) Select an audio device, and
2) Dial the number.
The SPA941 allows the user to perform these two steps in either order. In other words, the user can
select an audio device either before or after dialing.
The SPA941 supports two types of dialing: explicit or implicit. Explicit dialing refers to one of the following
cases:
• enter the target number digits one by one
• enter the speed dial assignment of the target number
• select an entry from a directory, and press the dial soft key
• press a dedicated key, such as the Voice Mail key
“Implicit dialing” refers to dialing a highlighted entry from one of the device’s directories or logs. A number
can be implicitly dialing by selecting an audio device while the number is highlighted on the display.
If an audio device is selected prior to dialing, then only explicit dialing is supported. Both explicit and
implicit dialing are allowed if the audio device is selected after dialing. Explicit dialing before the audio
device is selected is called “on-hook dialing”.
When an audio device is selected before dialing, a call appearance (for making the call) is also indirectly
selected. The SPA941 will pick the first available call appearance, in descending order, starting with Line
Key One. If no call appearances are available, no audio devices are selected.
A call appearance can be explicitly selected by pressing the corresponding line key. An audio device is
selected automatically based on the device’s programmed preferences. (Set by pressing menu Æ
Preferences Æ Preferred Audio Device, or by accessing the User tab of the web based interface.
Answering Calls
A line key LED rapidly blinks red when a call is incoming. The user can answer the call by:
•Selecting an audio device.
The SPA941 will answer the ringing call. If there are simultaneous incoming calls, the call ringing on
the lowest numbered line key is answered.
•Pressing the corresponding Line Key. The default audio device will be automatically selected.
Ending Calls
When a call is in the active state (not on hold or parked), the call can be ended by turning off the currently
selected audio device. A call in a standby state cannot be ended; it must be brought back to the active
state first.
Hold and Resume
An active call can be placed on hold by
• explicitly pressing the Hold key, or by
• pressing another Line Key (to answer an incoming all, resume a held call, or start a new call).
When a call is on hold, the corresponding Line Key LED slowly blinks red. To resume a call that is on
hold, press the corresponding Line Key.
When the phone is hosting a three way conference, two call appearances are in the connected state.
Pressing the Hold key places both calls on hold. The calls can be individually brought back to the
connected state by pressing the corresponding Line Keys.
Call Waiting
The Call Waiting function is activated when a device has a call in the active state and another call is
incoming. The phones in the SPA series do not support multiple calls on the same Line Key. Incoming
calls are assigned to an unused Line Key, causing the Line Key to quickly blink red. (Note that the Voice
Mail Waiting Indicator also blinks red whenever there is an incoming call.) The phone will not ring.
However, to alert the user, the call waiting tone is played into the active audio device.
The SPA941 allow multiple lines to simultaneously cause Call Waiting. All four call appearances can ring
at the same time, after one of the Extension Keys is answered, the other three call appearances will go
into the Call Waiting state.
Three Way Conferencing
There are two ways to initiate a three way conference on the SPA941:
•During an active call, if the phone has one or more idle call appearances, press the conf soft key.
This places the active call on hold and selects the next available call appearance for dialing (the dial
tone is heard in the active audio device). Dial the third party, the party to be added to the conference
call. After the third party’s line rings or is answered, presses the conf soft key again to join the two
calls into a conference.
•If the phone has a call is on hold while another call is either ringing or is connected, the confLx soft
key appears. If the phone has only one call on hold, pressing the confLx soft key joins the call on
hold with the active call. If the phone has more than one call on hold, pressing the confLx soft key
places the active call on hold and prompts the user to select the other Line Key to join with the
conference call.
Once the conference starts, the SPA941 plays a special brief tone to all three parties to indicate that a
conference call is in progress. The initiator of the conference call can terminate it at any time by hanging
up. The initiator leave the conference without ending the call by pressing join soft key; this allows the
other two parties to continue the call. This is implemented as a call transfer, which may not work if the
other two parties are hosted by different service providers.
Note: If the extension is configured with an external Conference Bridge URL, then conference is not
limited to three way; it can be as many parties as the conference bridge supports. There are two
restrictions that apply when using an external conference bridge:
1) The conference can only be initiated (by pressing the conf soft key) when the third party has
answered, instead of when the phone is either ringing or answered, and
2) Ringing call cannot be brought into a conference by pressing the confLx soft key; only calls that
are on hold can be brought into the conference with the confLx soft key.
Attended Call Transfer
An attended call transfer allows a user to optionally transfer a call to a third party, after having a
discussion with that third party. There are two ways to perform an attended call transfer:
•During an active call, press the xfer soft key to place the current call on hold and to activate an idle
Line Key. Dialed the transfer target number on the newly activated line. When the target is either
ringing or answered, press the xfer soft key again to complete the transfer.
•While one or more call appearances is on hold, initiate a call on an idle Line Key. While the call is
either ringing or is connected, press the xferLx line key. If only one other call is on hold, the active
call is connected with the call on hold. Otherwise, the user is prompted to select which Line Key to
transfer the call to.
Notes:
•At the completion of call transfer operation, the holding call peer will be the transferee, and the
connected or proceeding call peer will be the transfer target.
•The case where a call transfer is completed when the transfer target is ringi ng is called a semi-
attended call transfer. This is different from a blind transfer which is described in the next subsection.
Blind Call Transfer
A blind transfer allows the user to transfer a call without speaking with the receiver of the transferred call.
For the user, the call ends as soon as the transfer target’s phone number is dialed. The underlying
mechanism is the user’s phone sends the contact information for the transfer target to the phone of the
other party on the call. The information is carried in a signaling message. When the message is sent, the
user’s phone is dropped from the call and the other party’s phone automatically dials the transfer target.
To perform a blind transfer press the bxfer soft key and then dial the target number. The bxfer soft key
will automatically become active during a call, but it may not be visible on the display. If the bxfer key is
not visible, press the left / right direction arrows on the directional rocker know until it scrolls onto the
display.
Some older SPA phones do not have bxfer soft keys. To perform a blind transfer on these older devices,
during the call, press the xfer soft key, or the Line Key of an unused line. (There must be a spare line
available to perform the transfer.) Once the new dial tone is heard, enter *98; the phone will prompt the
user to enter the phone number of the transfer target. Enter the number to complete the blind transfer. If
the user’s phone has more than one call on-hold on, the last call placed on hold will be the on e
transferred.
Call Back
This service mimics the call back service offered by the PSTN. The user can activate this service on a
busy number such that he will be called back as soon as the busy number becomes available. The
SPA941 (and other members in the SPA family) implements this feature by repeatedly dialing the busy
number periodically until the called party rings or answers, or until the service order is canceled by the
user or expires. For that reason, it is better referred to as the repeat dialing service.
To activate this service, the user selects a Line key and enters *66 (Call back activation code). The
SPA941 then uses this call appearance to call the last called number. The retry period and expiration time
are configurable. To cancel the service, the user picks up any line and enter *86. When call back service
is active, the corresponding Line key will blink in green. The user can still use this line to make or answer
calls; when that happens the call back service is temporarily paused until the call appearance is idle
again.
When the call back number rings or answers, the call appearance will ring also like a normal incoming call
(the ring to be used is the default ring for the corresponding extension for that Line key). If the call back
party answers the call before the local user does, the SPA941 sends holding tone to the call back party. If
the local user picks up the call back Line key first, he will hear ring back tone like a regular outbound call.
Message Waiting Indication (MWI)
The SPA941 indicates message waiting in 2 ways:
1. Turning on the red MWI light - LED (with an envelope icon right above LED) on the phone.
2. Playing stutter tone instead of regular dial tone. The MWI light only applies to new message
indication received on Extension 1. It will not be turned on or off due to new message indication
received on the other Extensions [2 – 4]. On the other hand, the SPA941 can be configured to play a
stutter tone on the individual call appearance according to the message waiting state of the
corresponding Extension “X”.
Accessing Voice Mail
The SPA941 has a VM retrieval key for quick access to voice mail. If a voice mail access number or URL
is not specified, pressing the key brings up a screen where the user can enter the appropriate
information. This information can also be entered from the web page or downloaded via provisioning.
The SPA941 will attempt to call the voice mail number or URL if there is an idle call appearance available.
Muting Calls
The user can mute the audio input into the phone when an audio device is switched on, by pressing the
MUTE key. To un-mute, press the MUTE key again. If no audio device is on, pressing the MUTE key has
no effect. When switching from the speaker phone to the handset, the phone is automatically un-muted.
Shared Call Appearances
The SPA941 supports shared call appearances in association with a Broadsoft a pplication server. An
extension can be shared by two (2) or more stations. Any call appearances on a shared extension is a
shared call appearance. At any given time, each station sharing a call appearance can monitor the state
of the call appearance. A station can select a share call appearance to make a call only if the call
appearance is not being used by another station. All stations will ring on an inbound call to the shared
call appearance extension. Whoever picks up the call first will take the call. When a call is placed on
hold by one station, it can be resumed from another station sharing the same call appearance.
Additional methods for shared call appearances per vendor application server implementation are being
added to the SPA941 and will be available in future firmware releases. Please contact sales@linksys.com
to inquire about roadmap / development schedules.
•A Line Key corresponds to a call appearance. Call appearances for the same extension are
numbered in ascending order of their Line Key position starting at 1. The Line Key LED color and
blinking pattern are fully programmable. The administrator can specify a different color and
pattern for each well-defined states of the call appearance. These states are described below.
• Idle: This call appearance is not in use. The user can use it to make outbound call on this station
• Local Seized: This call appearance has been seized by this station to prepare for an outbound
call
• Local Progressing: This station is making an outbound call that is progressing
• Local Active: This station is engaged in a connected call on this call appearance
• Local Ringing: This station is ringing for an incoming call on this call appearance
• Local Held: This station has placed this call appearance on hold
• Remote Seized: This call appearance has been seized by another station to prepare for an
outbound call
• Remote Progressing: Another station is making a call on this call appearance and is progressing
• Remote Active: Another station is engaged in a connected call on this call appearance
• Remote Ringing: Another station is ringing for an incoming call to this call appearance
• Remote Held: Another station has placed this call appearance on hold
• Remote Undefined: The share call state is not known (this station is waiting for a notification from
the application server)
•Registration Failed: This station has failed to register with the proxy server for the corresponding
extension
•Registering: The station is attempting registration with the proxy server for the corresponding
extension.
• Disabled: This Line Key on this station is disabled
• Call Back: A call back (repeat dialing) operation is currently active on this call appearance
The Line Key LED supports 4 colors: Red (r), Green (g), Amber (a), and Off (o). The SPA941 has 4 builtin blinking patterns defined:
• No Blink (nb): Steady on (or off)
• Slow Blink (sb): 500ms on, 500ms off
• Fast Blink (fb): 100ms on, 100ms off
• Double Blink (db): 100ms on, 100ms off, 100ms on, 700ms off
The administrator can also define arbitrary blinking pattern by following the syntax of a LedScript. The
default LedScript for each call appearance state is described in section 3.
The SPA941 supports the following supplementary Services:
Block Caller ID
If enabled, the SPA941 will attempt to hide the caller-ID on all outbound calls by default. The user can
also enable or disable this feature on a per call basis by pre dialing a *code befo re making the call.
Block Anonymous Call
Reject all inbound calls with no caller-ID with a 406 response
Do Not Disturb (DND)
Reject all inbound calls as if the phone is busy. That is, the phone either responds a 302 if call forward on
busy if enabled, or 486 otherwise.
Secure Call
If enabled, the SPA941 will try to negotiate on all outbound calls to use encrypted media (SRTP) by
default. The user can also enable or disable this feature on a per call basis by pre dialing a *code before
making the call. Note that in order to use Secure Call on an extension, <Mini Certificate> and <SRTP
Private Key> must be configured for that extension.
The enabling and disabling of these services applies to calls on all configured extensions on the SPA941
Secure Call Implementation:
A secure call is established in two stages. The first stage is no different form a normal call setup. Right
after the call is established in the normal way with both sides ready to stream RTP packets, the second
stage starts where the two parties exchange information to determine if the current call can switch over to
the secure mode. The information is transported by base64 encoding and embedding in the message
body of SIP INFO requests and responses with a proprietary format. If the second stage is successful, the
SPA will play a special “Secure Call Indication Tone” for short while to indicate to both parties that the call
is secured and that RTP traffic in both directions are encrypted. The phone screen will be updated with
the CID information extracted from the Mini-Certificate received from the other end. The call state label on
the phone screen will also be prepended with a ‘$’ symbol (such as $Connected instead of Connected).
The second stage in setting up a secure all can be further divided into two steps. Step 1 the caller sends
a “Caller Hello” message (base64 encoded and embedded in the message body of a SIP INFO request)
to the called party with the following information:
Upon receiving the Caller Hello, the callee responds with a Callee Hello message (base64 encoded and
embedded in the message body of a SIP response to the caller’s INFO request) with similar information, if
the Caller Hello message is valid. The caller then examines the Callee Hello and proceeds to step 2 if the
message is valid. In step 2 the caller sends the “Caller Final” message to the callee with the following
information:
- Message ID (4B)
- Encrypted Master Key (16B or 128b)
- Encrypted Master Salt (16B or 128b)
With the master key and master salt encrypted with the public key from the callee’s mini-certificate. The
master key and master salt are used by both ends for the derivation of session keys for encrypting
subsequent RTP packets. The callee then responds with a Callee Final message (which is an empty
message).
A Mini-Certificate contains the following information:
- User Name (32B)
- User ID or Phone Number (16B)
- Expiration Date (12B)
- Public Key (512b or 64B)
- Signature (1024b or 512B)
The signing agent is implicit and must be the same for all SPA’s that intended to communicate securely
with each other. The public key of the signing agent is pre-configured into the SPA’s by the administrator
and will be used by the SPA to verify the Mini-Certificate of its peer. The Mini-Certificate is valid if a) it has
not expired, and b) its signature checks out.
User Interface
The SPA can be set up such that all outbound calls are secure calls by default, or not secure by default. If
outbound calls are secure by default, user has the option to disable security when making the next call by
dialing *19 before dialing the target number. If outbound calls are not secure by default, user has the
option to make the next outbound call secure by dialing *18 before dialing the target number. On the other
hand, user cannot force inbound calls to be secure or not secure; it is at the mercy of the caller whether
he/she enables security or not for that call.
If the call successfully switches to the secure mode, both parties will hear the “Secure Call Indication
Tone” for a short while and the CID will be updated with the Name and Number extracted from the MiniCertificate sent by the other partyThe callee should check the name and number again to ensure the
identity of the caller. The caller should also double check the name and number of the callee to make
sure this is what he/she expects. Note that the SPA will not switch to secure mode if the callee’s CID
Number from its Mini-Certificate does not agree with the user-id used in making the outbound call: the
caller’s SPA will perform this check after receiving the callee’s Mini-Certificate.
The SPA Mini-Certificate (MC) has a 512-bit public key used for establishing secure calls. The
administrator must provision each subscriber of the secure call service with an MC and the corresponding
512-bit private key. The MC is signed with a 1024-bit private key of the service provider who acts as the
CA of the MC. The 1024-bit public key of the CA signing the MC must also be provisioned to each
subscriber. The CA public key is used by the SPA to verify the MC received from the other end. If the MC
is invalid, the SPA will not switch to secure mode. The MC and the 1024-bit CA public key are
concatenated and base64 encoded into the single parameter <Mini Certificate>. The 512-bit private key is
base64 encoded into the <SRTP Private Key> parameter, which should be hidden from the SPA’s web
interface like a password.
Since the secure call establishment relies on exchange of information embedded in message bodies of
SIP INFO requests/responses, the service provider must maker sure that their infrastructure will allow the
SIP INFO messages to pass through with the message body unmodified.
Linksys provides a configuration tool called gen_mc for the generation of MC and private keys with the
following syntax:
- ca-key is a text file with the base64 encoded 1024-bit CA private/public key pairs for signing/verifying
the MC, such as
9CC9aYU1X5lJuU+EBZmi3AmcqE9U1LxEOGwopaGyGOh3VyhKgi6JaVtQZt87PiJINKW8XQj3B9Qqe3V
gYxWCQNa335YCnDsenASeBxuMIEaBCYd1l1fVEodJZOGwXwfAde0MhcbD0kj7LVlzcsTyk2TZYTccnZ7
5TuTjj13qvYs=
5nEtOrkCa84/mEwl3D9tSvVLyliwQ+u/Hd+C8u5SNk7hsAUZaA9TqH8Iw0J/IqSrsf6scsmundY5j7Z5mK5J
9uBxSB8t8vamFGD0pF4zhNtbrVvIXKI9kmp4vph1C5jzO9gDfs3MF+zjyYrVUFdM+pXtDBxmM+fGUfrpAu
Xb7/k=
- user-name is the name of the subscriber, such as “Joe Smith”. Maximum length is 32 characters
- user-id is the user-id of the subscriber and must be exactly the same as the user-id used in the INVITE
when making the call, such as “14083331234”. Maximum length is 16 chara cters.
- expire-date is the expiration date of the MC, such as “00:00:00 1/1/34” (34=2034). Internally the date is
encoded as a fixed 12B string: 000000010134
The tool generates the <Mini Certificate> and <SRTP Private Key> parameters that can be provisioned to
4. Press SK(save) to save the entry in the personal directory
The SPA941 keeps up to 60 entries per log in reverse chronological order. The logs are saved in the
phone’s non-volatile memory.
All call logs can be viewed on the SPA941 web page also using the link:
http://<ip-address./calllog.htm
Each log is shown on the web page with the syntax: [ext-id]name, phone, time-stamp
•ext-id is the extension on which the call is made from or received at (E1, E2, E3, or E4). If [En] is
not present, it implies [E1].
• name is the call peer’s name. If this field is missing, the peer’s name is not available
• phone is the call peer’s phone number (user-id). If this field is missing, the peer’s phone num ber
is not available
•t is the time-stamp at which the call log is entered. It has the format mm/dd hh/mm<a|p> (where a
= am and p = pm
Example 1: [E2]Joe Smith,14089991234,t=10/12 11:12a
Example 2: 14089991234,10/12 01:12p
(On E1; name not available)
Personal Directory
A directory entry consists of the following information:
• Name
• Phone number or (SIP) URL
• Ring Tone
Up to 100 entries can be stored in the SPA941. An entry can be added or edited from the phone GUI or
on the web page or through remote provisioning. To do this from the web page or through remote
provisioning, you specify the value as a DirEntry script. To view or edit the personal directory via the
phone web interface, use the link
The user can invoke the Directory menu on the phone in 2 ways: a) Press the menu button and select
“Directory”, or b) Press SK(dir) when you’re not already in a SETUP screen. The user can add a new
entry to the Directory by selecting the “New Entry” option (the first item) on the Directory menu and press
SK(add). To modify or delete an existing item, highlight the corresponding entry and press SK(edit) or
SK(del). When trying to delete an entry, the phone will prompt the user for confirmation before
proceeding.
The user can copy an existing directory entry to create a new entry. To do this, high light the entry you
want to copy and press SK(copy). Then high light the “New Entry” option and press SK(paste). The user
can edit the new entry and then press SK(save) to save the entry.
The user can also save a call log entry into the directory. To do this, select a call log entry and press
SK(save). Then edit the entry if needed, and then press SK(save) to save the new entry in the directory.
Entering and Saving Settings
The SPA941 GUI allows the user to enter alphanumeric and numeric inputs will ease. The following data
types may be entered into the phone:
• Numeric String, such as a phone number when dialing
• Alphanumeric String, such a name when adding a Directory entry
• IP Address, such as a DNS server IP address
• Boolean (y/n), such as enabling or disabling DHCP
• Option, such as selecting a preferred audio device or a ring tone
When any two or more of the numeric string, alphanumeric string, and IP address types can apply to an
entry, the phone will show a soft key for switching input modes among the applicable types. The soft keys
will change when pressed to allow the user to scroll through the available modes, such as SK(num) Æ
SK(alpha) Æ SK(IP). The cursor will also change according to the following table, to remind the user
which input mode is being used:
Numeric num Blinking underscore _ Blinking vertical line |
Alphanumeric alpha
IP Address IP
When entering digits during numeric mode, just enter the corresponding digits from the key pad.
When entering letters or symbols during alphanumeric mode, the phone will show a template of 2 or more
choices of symbols as the user presses each digit key; the user can scroll through the choices by
pressing the same key multiple times. To accept a symbol as input, the user can a)stop pre s sing the digit
key for 1.5s, b)pressing another digit key, c)navigate to another input field (if applicable) by pressing the
UP/DOWN key, or d)save the value by pressing the proper soft key, such SK(save) or SK(ok)
When entering IP address, pressing the * digit will insert a dot (.), or a colon (:) if there are 3 dots entered
already.
When entering numeric, alphanumeric, or IP address values, the following additional soft keys will be
available for easier editing:
• SK(<<) – Move cursor to the left by 1 character
• SK(>>) – Move cursor to the right by 1 character
• SK(erase<) – Erase the character to the left of the cursor
Note that SK(<<), SK(>>), SK(erase<), and the digit key presses will automatically repeat by keep
pressing the corresponding key down without releasing it. If input value is wider than what the LCD
display can show, the SPA941 automatically scroll the input to the left so that the user can continue to
enter input. On the other hand, the SPA941 will stop accepting further input for a give field if the
maximum allowed input length has been reached for that input field.
For Boolean input, the SPA941 will show SK(y/n) pressing which will toggle the current input between yes
and no.
For Option input, the SPA941 will show SK(option) pressing which will either a) change the input field to
the next available choice in round-robin fashion, or b) bring up a menu of choices that the user can select
from.
For most settings, the input value is saved once the user press SK(save) or SK(ok) before exiting the edit
screen for that setting. However, there are a few exceptions where the user must press SK(save) again at
the upper level when all the required changes have been made to the settings so that they are saved into
the configuration at the same time. These exceptions are:
Preferences
• Call Forward
• Network
Speed Dialing
The SPA941 has eight programmable speed dial numbers which can be set either through the GUI, or
through the User tab of the phone’s web page. To use the GUI to configure the speed dial, select the
Speed Dial entry after pressing menu key. The speed dial numbers are assigned to the digits two
through nine. If a slot is not configured, it will show <Not Assigned> on the entry. Highlight the speed dial
entry you want to add or modify, press SK(edit) to make the changes, and press SK(ok) to store the
value.
A speed dial entry can be a phone number or URL. The user can also enter a name that matches one of
the directory entries. As you enter the value, the SPA941 will attempt to match the entry to the directory
entries and brings up a list of potential matches on the screen. User can scroll down to select one of the
suggested entries.
To dial a speed dial, dial the corresponding single digit like a 1-digit phone number. The user can enter
“#” after the speed dial number but it is not necessary.
When making an outgoing call, SPA941 will try to find the dialed number in the personal directory first,
and then from the missed call log, and finally from the answered call log. If a match is found and the
name field is present in the matched entry, it will be shown on the call screen as the called peer’s name.
For incoming calls, SPA941 will try to find the caller’s phone number in the personal directory. If a match
is found and the name field is present in the matched entry, it will replace the current caller ID name and
will be shown on the call screen as the calling peer’s name. The same name will also go into the incoming
call log. If a match is not found, or the name field is not present in the matched entry, the current caller ID
name will be used if it exists.
Dialing Assistance
Dialing assistance is an option the user can enable or disable under the Preferences menu. If the option
is enabled, the phone will show up to ten potential matches from the Redial List (most recent first) and
from the Personal Directory as the user dials the target number. This feature applies to both off-hook
(with dial tone) and on-hook (without dial tone) dialing. When the suggestion list appears, the user can
scroll down the list using the Up/Down key to select the desired target number from the list.
When looking for matches from the Redial List and the Directory, the SPA941 will skip any leading
*codes, so that the match is purely based on the target number. The *code that will be skipped are (if
configured in the phone):
• All call forward activation and deactivation codes
• Secure call activation and deactivation codes
• Block CID activation and deactivation codes
• Block anonymous call activation and deactivation codes
• DND activation and deactivation codes
• All the Prefer codec and Force codec codes
• Referral services codes and Feature Dial Services codes
Time/Date
The SPA941 obtains the current time information from one of the following ways:
•NTP Server – One or two NTP servers can be configured to the phone. When it first boots up, the
phone will try to contact the NTP server to get the current time. Then the phone periodically
synchronizes the current time with the NTP server. The synchronization period is fixed at 1 hour.
In between the update, the phone tracks the time with its own internal clock.
•SIP Messages – Each SIP message (request or response) sent to the SPA may contain a Date
header with the current time information. If the header is present, the SPA will use it to update its
current time.
•Manual Setup – SPA941 also allows the user to manually enter the current time and date from
the phone GUI or from the web page. However, this value will be overridden by the NTP time or