2N BRI Lite/Enterprise v1.2 User Manual

2N® BRI Lite/Enterprise

BRI-VoIP-GSM/UMTS Gateway

User Manual

Version	1.2
Firmware	1.5.0	www.2n.cz

The 2N TELEKOMUNIKACE joint-stock company is a Czech manufacturer and supplier of telecommunications equipment.

The product family developed by 2N TELEKOMUNIKACE a.s. includes GSM gateways, private branch exchanges (PBX), and door and lift communicators. 2N TELEKOMUNIKACE a.s. has been ranked among the Czech top companies for years and represented a symbol of stability and prosperity on the telecommunications market for almost two decades. At present, we export our products into over 120 countries worldwide and have exclusive distributors on all continents.

2N® is a registered trademark of 2N TELEKOMUNIKACE a.s.. Any product and/or other names mentioned herein are registered trademarks and/or trademarks or brands protected by law.

2N TELEKOMUNIKACE administers the FAQ database to help you quickly find information and to answer your questions about 2N products and services. On www.faq.2n.cz you can find information regarding products adjustment and instructions for optimum use and procedures „What to do if...“.

Declaration of Conformity

2N TELEKOMUNIKACE hereby declares that the 2N® BRI Lite/Enterprise product complies with all basic requirements and other relevant provisions of the 1999/5/EC directive. For the full wording of the Declaration of Conformity see the CD-ROM enclosed and at www.2n.cz.

The 2N TELEKOMUNIKACE company is the holder of the ISO 9001:2009 certificate. All development, production and distribution processes of the company are managed by this standard and guarantee a high quality, technical level and professional aspect of all our

Content
1. Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		5
1.1	Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	6
1.2	Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	9
1.3	Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	10
1.4	Terms and Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	11
2. Description and Installation . . . . . . . . . . . . . . . . . . . . . . . . . .		12
2.1	Before You Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
2.2	Brief Installation Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	17
2.3	Available ISDN BRI Extension Configurations . . . . . . . . . . . . . . . . . . . . . . . . . .	24
2.4	IP Voice Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	25
2.5	Types of 2N® BRI Enterprise Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	28
3. Making Calls via BRI Gateway . . . . . . . . . . . . . . . . . . . . . . . .		31
3.1	Supported 2N BRI Gateway Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	32
3.2	Call Routing Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	33
4. First Launch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		37
4.1	Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	38
4.2	Licence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	40
4.3	Firmware Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	41
4.4	Factory Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	42
4.5	Basic Configuration – Step by Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	43
5. Introduction to Configuration Interface . . . . . . . . . . . . . . . .		44
5.1	Configuration Web Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	45
6. Configuration Via Terminal . . . . . . . . . . . . . . . . . . . . . . . . . .		70
6.1	LAN Communication Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	71
6.2	GSM Gateway Behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	72
6.3	List of Terminal AT Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	73
6.4	Status Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	80
6.5	LOG Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	86
6.6	Call Data Records (CDR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	89
6.7	Statistics - Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	90

7. Technical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

8. Supplementary Information . . . . . . . . . . . . . . . . . . . . . . . . . . 94

8.1	Directives, Laws and Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	95
8.2	Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	96
8.3	List of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	97
8.4	General Instructions and Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	99

1. Product Overview

In this section, we introduce the 2N® BRI Lite / Enterprise product, outline its application options and highlight the advantages following from its use.

Here is what you can find in this section:

1.1	Product Description
1.2	Safety Precautions
1.3	Upgrade
1.4	Terms and Symbols Used

2N® TELEKOMUNIKACE a.s., www.2n.cz

1.1 Product Description

The 2N® Enterprise / BRI Lite GSM gateway provides direct interconnection of the ISDN with GSM networks. It can also be used for direct interconnection of an ISDN PBX with a GSM network, ISDN telephone set and, via a terminal adapter, with an analogue apparatus or coin machine. The voice mode, i.e. outgoing and incoming calls, is the basic function of the gateway. Moreover, the BRI gateway provides connection to the VoIP–SIP networks. The gateway is equipped with all functions necessary for this mode and is very user–friendly. In addition, 2N® BRI Enterprise / BRI Lite allows you to send and receive SMS messages. No additional devices (an external telephone, e.g.) are required for normal operation. All gateway parameters can be set using a configuration program (on an enclosed CD), or using the AT commands. Programmable parameters are pre–set to make it possible to make calls as soon as the supply cable, antenna a SIM cards are connected.

2N® BRI Enterprise / 2N® BRI Lite Differences

The 2N® BRI Enterprise and 2N® BRI Lite gateways are based on one and the same type of hardware and apply identical firmware and control (configuration) software. The only difference lies in the count of BRI ISDN interfaces:

Interface	2N® BRI Lite	2N® BRI Enterprise
BRI ISDN	1 (NT/TE)	2 (1 TE ; 1 NT)
Ethernet	YES*	YES*

*The VoIP–SIP support depends on Part No. (subject to licence).

Telephone Cost Cuts

Having connected 2N® BRI Enterprise / BRI Lite to your ISDN PBX, you can make calls to the mobile network directly. This saves your PSTN – GSM connection costs.

You do not pay for barred calls. You can set groups of barred numbers in the gateway.

A flexible setting of the Least Cost Router helps you call GSM numbers at minimum operational costs.

You can route calls to alternative providers' networks via the VoIP/SIP interface.

As all gateway user calls are added up for billing purposes, you are advised to use the most advantageous tariff offered by your provider.

2N® TELEKOMUNIKACE a.s., www.2n.cz

2N® BRI Enterprise / 2N® BRI Lite Basic Features

Integration of the best features of two communication technologies: ISDN and GSM

VoIP–SIP telephony support with G.711a/u and G.729ab codecs1

Intelligent routing of incoming and outgoing calls

Web interface for gateway configuration and SMS sending/receiving

Automatic no answer SMS sending for GSM networks

Automatic missed call SMS in the GSM network

Simple recording of a welcome note, DISA voice message

Automatic recording of call data and detailed statistics (CDR)

ENBLOCK/OVERLAP ISDN dialling switch option

Monitoring of ISDN BRI line statuses and alarm SMS sending option

Automatic sending of Alive SMS in user–defined intervals

Easy firmware upgrade via a configuration program

External synchronising source connection option (BRI Enterprise) Mobility Extension2 support.

[1]Depending on the licence

[2]Will be available in early 2013

DialThru (2N® BRI Enterprise)

The difference between 2N® BRI Enterprise and 2N® BRI Lite lies in the DialThru functionality. DialThru enables the gateway to be connected between the PBX and the voice service provider line, i.e. PSTN. The GSM gateway in the DialThru mode routes, based on the LCR, calls into the PSTN or GSM/UMTS networks.

Refer to the figure below for a schematic diagram of the 2N® BRI Enterprise connecti on.

The gateway works as a dial–through router (using both the TE and NT ports in the DialThru

2N® TELEKOMUNIKACE a.s., www.2n.cz

mode) for calls to a mobile network, and a monitoring system, which, with the appropriate licence, sends SMS to the provider (in the case of line unavailability, e.g.). The 2N® BRI Lite GSM gateway contains just one ISDN BRI port and thus cannot work in the DialThru mode. It can be connected to a PBX on a trunk line or extension and route calls to the GSM/UMTS networks only – see the figure below.

2N® TELEKOMUNIKACE a.s., www.2n.cz

1.2 Safety Precautions

It is prohibited to use any transmitters, including the GSM/UMTS gateways, in areas where explosives are used, such as quarries.

It is prohibited to use the 2N® BRI Enterprise / BRI Lite GSM gateways at petrol stations where mobile telephones are also prohibited.

GSM phones may affect sensitive life–saving devices in medical centres. Therefore, it is forbidden to use GSM/UMTS devices, including the GSM gateways, in such facilities.

In general, any prohibition regarding mobile phones based on RF energy radiation applies to GSM/UMTS devices too.

If necessary, the GSM gateways may be installed at a safe distance from the prohibited area and connected with the original place through an Ethernet cable.

Although GSM gateways are not intended for cars or aeroplanes, all relevant prohibitions and regulations regarding mobile phones apply to them too.

2N® TELEKOMUNIKACE a.s., www.2n.cz

1.3 Upgrade

The manufacturer reserves the right to modify the product in order to improve its qualities.

In response to the customers' requirements, the manufacturer constantly improves the software contained in the product (firmware). For the latest 2N® BRI Enterprise / 2N® BRI Lite firmware version and the User Manual refer to the 2N web sites.

Refer to the S. 2, Description and Installation, for a detailed description of the 2N® BRI Enterprise / 2N® BRI Lite firmware upgrade.

Manual

Version

1.0

Changes

The User Manual relates to the 2N® BRI Enterprise / BRI Lite firmware version 1.5.0.

2N® TELEKOMUNIKACE a.s., www.2n.cz

1.4 Terms and Symbols Used

Manual Symbols

Safety

Always abide by this information to prevent persons from injury.

Warning

Always abide by this information to prevent damage to the device.

Caution

Important information for system functionality.

Tip

Useful information for quick and efficient functionality.

Note

Routines or advice for efficient use of the device.

Future Functions, Innovations

The grey-marked text in this document designates the functions that are under preparation or development at present.

2N® TELEKOMUNIKACE a.s., www.2n.cz

2. Description and Installation

This section describes the 2N® BRI Enterprise / 2N® BRI Lite product and its installation.

Here is what you can find in this section:

2.1 Before You Start

2.2 Brief Installation Guide

2.3 Available ISDN BRI Extension Configurations

2.4 IP Voice Transmission

2.5 Types of 2N® BRI Enterprise Connection

2N® TELEKOMUNIKACE a.s., www.2n.cz

2.1 Before You Start

Caution

Make sure that you are equipped with all system components necessary for putting 2N® BRI Enterprise / Lite in operation (SIM card, ISDN phone and/or duly configured ISDN BRI line of your PBX or PSTN, an available Ethernet/USB socket and a PC for initial gateway configuration).

Product Completeness Check

Before installing this product, check whether the 2N® BRI gateway delivery complies with the following packing list:

Package	BRI Lite	BRI Enterprise
2N® BRI Enterprise / Lite	1	1
Power supply adapter	1	1
Long antenna	1 – 2*	1 – 2*
Ethernet cable	1	1
BRI ISDN cable	1	2
Wall mounting set	1	1
*depends on the Part No.

Connector Lay–Out – Lower Side

The following connectors are available on the BRI gateway bottom:

Connector type	BRI Lite	BRI Enterprise
DC Jack 2.1mm supply connector	YES	YES
10/100BaseT Ethernet connector	YES	YES
ISDN BRI TE interface	NO	YES
ISDN BRI NT interface	NO	YES
ISDN BRI NT/TE interface	YES	NO

2N® TELEKOMUNIKACE a.s., www.2n.cz

Caution

2N® BRI Lite has two RJ45 connectors, which, however, are cross–connected into one ISDN BRI. Be sure to connect just one ISDN BRI line to make the system work properly. Which of the RJ45 connectors will be used depends on the type of the equipment to be connected (NT/TE) and the interconnecting cable (cross/straight).

Connector Lay–Out – Upper Side

There are SMA female antenna connectors to each GSM/UMTS module on the 2N® BRI Enterprise / Lite upper side.

Status LED Indicators – 2N® BRI Lite

The 2N® BRI Lite status is indicated by five LEDs on the front side. BRI 1 and BRI 2 indicate the status of ISDN BRI B–channels and CH 1 and CH 2 indicate the status of each GSM/UMTS module. Refer to the table below for the statuses

2N® TELEKOMUNIKACE a.s., www.2n.cz

LED Indicators

Power supply

GSM/UMTS network

ISDN port

Ethernet port

green light – mains powered no light – device switched off

green light – call in progress red light – error

green flashing – network registration, SMS red flashing – module restart

Red/green flashing – signal intensity indication

green light – 2 calls in progress

green flashing – ISDN synchronisation/active call red light – ISDN disconnected

red flashing – synchronisation of lower ISDN layers

green light + no orange light – disconnected

green light + orange flashing – 100BaseT connected, in operation

no green light + orange light – 10baseT connected, no operation green flashing + orange flashing – 10BaseT connection, in operation

Signal

Signal intensity indication:one segment = less than –109dbmtwo

intensity

segments = more than –95dbmthree segments = more than –81dbmfour segments = more than –65dbm

*If the devices have been interconnected, the layers will not be connected until the first call.

Status LED Indicators – 2N® BRI Enterprise

The 2N® BRI Enterprise status is indicated by five LEDs on the front side. BRI 1 and BRI 2 indicate the status of ISDN BRIs and CH 1 and CH 2 indicate the status of each GSM/UMTS module. Refer to the table below for the statuses.

2N® TELEKOMUNIKACE a.s., www.2n.cz

LED Indicators

Power supply

GSM/UMTS network

ISDN port

Ethernet port

green light – mains powered no light – device switched off

green light – call in progress red light – error

green flashing – network registration, SMS red flashing – module restart

Red/green flashing – signal intensity indication

green light – 2 calls in progress

green flashing – ISDN synchronisation/active call red light – ISDN disconnected

red flashing – synchronisation of lower ISDN layers

green light + no orange light – disconnected

green light + orange flashing – 100BaseT connected, in operation

no green light + orange light – 10baseT connected, no operation green flashing + orange flashing – 10BaseT connection, in operation

Signal

Signal intensity indication:one segment = less than –109dbmtwo

intensity

segments = more than –95dbmthree segments = more than –81dbmfour segments = more than –65dbm

* If the devices have been interconnected, the layers will not be connected until the first call.

**Remember to set the signal intensity indication in the gateway configuration menu.

Potential GSM/UMTS Troubles

All 2N® GSM gateways work reliably under a long–time full load. The following problems may be caused by GSM/UMTS networks:

The GSM/UMTS module(s) cannot log in, log in slowly, or log out occasionally. This problem may be caused by any of the following situations:

The GSM/UMTS signal is low. The minimum signal level should be approximately –80dBm. If lower, change the antenna position or type!

The GSM/UMTS cell (BTS) to which the GSM/UMTS modules are trying to log in is overloaded. Change the antenna position or reduce the count of the logged–in GSM/UMTS modules.

One of the GSM/UMTS modules is permanently logged–out or fails to make outgoing calls:

The problem indicates a GSM/UMTS network overload on the installation site. To eliminate the problem, set the Relax delay parameter to 2 seconds. If the GSM module fails to log in or rejects to make outgoing GSM calls even after the gateway restart, consult your GSM provider for your SIM card/GSM module availability.

The manufacturer shall not be held liable for any SIM card or provider service unavailability in the case of a breach of the provider's SIM terms and conditions for the SIM card use.

2N® TELEKOMUNIKACE a.s., www.2n.cz

2.2 Brief Installation Guide

Installation Conditions

The following installation conditions have to be met for a proper installation:

2N® BRI Enterprise / BRI Lite is to be installed on a site with enough free space.

2N® BRI Enterprise / BRI Lite is to be mounted on a suitable vertical surface. For this purpose, a hanger is included in the gateway delivery, which is fitted to the wall using dowels and screws and used for gateway hanging.

It is possible to operate the gateway in another working position too, e.g. on a desk, for a short time for servicing and testing purposes, for example.

Any excess of the allowed working temperature may not affect the 2N® BRI Enterprise / BRI Lite function immediately but may result in faster ageing and lower reliability. For the allowed working temperature and humidity ranges refer to S. 7.

2N® BRI Enterprise / BRI Lite is not designed for high–vibration environments such as means of transport, machine rooms, and similar.

2N® BRI Enterprise / BRI Lite is not designed for dusty environments or places exposed to high humidity and temperature changes.

2N® BRI Enterprise / BRI Lite may not be exposed to aggressive gases, acid and solvent vapours (during cover cleaning, e.g.).

2N® BRI Enterprise / BRI Lite is intended for indoor use. It may not be exposed to rain, flowing water, condensing moisture, fog, and so on.

2N® BRI Enterprise / BRI Lite may never be exposed to direct sunshine or placed close to heat sources (radiators).

A sufficient clearance must be kept over and under 2N® BRI Enterprise / BRI Lite for cabling and air flow to carry off the heat.

A sufficient GSM/UMTS signal intensity has to be provided for 2N® BRI Enterprise / BRI Lite.

2N® TELEKOMUNIKACE a.s., www.2n.cz

An adequate capacity of the GSM/UMTS network has to be ensured (no BTS overload). Remember that multiple GSM gateways used in one location may overload the base transceiver station (BTS) you are currently logged in to. This may lead to a permanent or occasional rejection of GSM/UMTS calls!

No strong electromagnetic radiation is allowed on the 2N® BRI Enterprise / BRI Lite installation site.

No strong electromagnetic reflections are allowed on the 2N® BRI Enterprise / BRI Lite antenna installation site.

An inappropriate location of 2N® BRI Enterprise / BRI Lite or its antenna close to television, broadcasting and/or other rf–sensitive sets may impair the function of these sets.

Being a source of radio frequency emissions, the 2N® BRI Enterprise / BRI Lite antenna should not occur in the close vicinity of the human body. The health hazard is higher than with mobile phones as, generally, gateways shared by multiple users show a very high traffic.

It is recommended that the power supply adapter should be connected to a network with a UPS back–up and due overvoltage protection.

SIM Card Inserting/Removing

Insert the SIM card in the 2N® BRI Enterprise / BRI Lite bottom as shown in the figure. As the SIM slots are of the Push/Pull type, just slide the card in and push it into position. Push the SIM gently to slide it out of the slot.

2N® TELEKOMUNIKACE a.s., www.2n.cz

Caution

Be sure to set such provider/SIM card services as call forwarding, call barring, preferred networks, SMS centre, etc. in your mobile phone before inserting the SIM card into 2N® BRI Enterprise / BRI Lite.

If two SIM cards are used, make sure that both the SIM cards have one and the same PIN or PIN code request disable.

Having inserted the SIM card, restart 2N® BRI Enterprise / BRI Lite to make the SIM card log in.

Remember to disable the Another call on line service before using the SIM cards!

Antenna Connection

2N® BRI Enterprise / BRI Lite is equipped with a SMA female antenna connector for all the GSM/UMTS modules. The external antenna should always be installed vertically on a site with a good wireless signal.

Warning

Tighten the antenna connector gently with your hand – never use a wrench!

Being a source of radio frequency emissions, the 2N® BRI Enterprise / BRI Lite antenna should not be very close to the human body. The health hazard is higher than with mobile phones as, in general, gateways shared by multiple users show a very high traffic.

2N® TELEKOMUNIKACE a.s., www.2n.cz

Note

The antenna has a sufficient gain for a trouble–free operation under normal conditions. If the signal is poor or you want to place your antenna away from 2N® BRI Enterprise / BRI Lite , you can use an antenna with an SMA–connector terminated cable. The antenna should be mounted vertically.

Refer to S.7, Technical Parameters, for the antenna parameters.

Power Supply Connection

Use only the power supply adapter included in the delivery. Make sure that the electric distribution network voltage is in compliance with the data on the supply adapter plate before plugging the adapter and that the antenna is connected properly. If you connect the power supply without having connected the antenna, the GSM module transmitter may get damaged. Plug the supply adapter into the mains socket and only then connect the adapter connector to the gateway. Refer to the status indicators.

Warning

Connecting a defective or inappropriate power supply adapter may lead to a temporary or permanent 2N® BRI Enterprise / BRI Lite error!

Check whether the antenna is connected before plugging the adapter. Feeding the device without antenna connection may result in the GSM module transmitter damage.

2N® TELEKOMUNIKACE a.s., www.2n.cz

Ethernet Cable Connection

To connect 2N® BRI Enterprise/Lite into the Ethernet network, use a standard straight cable terminated with RJ–45 connectors (included in the package). The GSM gateway supports the 10BaseT and 100BaseT standards, the Ethernet connection status is indicated by the status LED indicators located on the RJ–45 connector (refer to S. 2.1 for details).

Caution

The Ethernet interface is used for remote supervision and configuration only, i.e. does not contain the VoIP interface. With a proper licence, the device provides the VoIP–SIP support.

RJ–45 LAN Connector

NT and TE Connectors

1 not used2 not used3 Tx4 Rx5 Rx6 Tx7 not used8 not usedISDN devices are connected to the NT/TE connectors depending on the configuration of your telecommunications equipment. They are connected via a 4–wire passive bus with the aid of RJ–45 connectors. Refer to the figure below for the NT/TE connector pin lay–out.

2N® TELEKOMUNIKACE a.s., www.2n.cz

TE connector The figure below shows 2N® BRI Enterprise / BRI Lite connected as network termination (NT) – extension for your ISDN PBX or ISDN phone, i.e. your own equipment.

The figure below shows 2N® BRI Enterprise / BRI Lite connected as terminal equipment (TE) – extension from the ISDN (PSTN), i.e. from your service provider.

An example of the 2N® BRI Enterprise connection in the ISDN mode follows.

2N® TELEKOMUNIKACE a.s., www.2n.cz

Caution

2N® BRI Lite is equipped with just one ISDN BRI. Hence, two independent devices cannot be connected at the same time!

2N® TELEKOMUNIKACE a.s., www.2n.cz

2.3 Available ISDN BRI Extension

Configurations

You have to know the way of connection of your ISDN devices in order to configure your 2N® BRI Enterprise / BRI Lite GSM gateway correctly. For information on your ISDN type, check your ISDN extension provider's registration form or contact your telephone network administrator.

Point–to–Point Configuration

The Point–to–Point (EuroISDN with DDI) configuration interconnects directly one ISDN terminal (TE) and a network terminal (NT) (see the figure below). This type is applied mainly where PBXs are connected to the ISDN.

Point–to–Multipoint Configuration

Point–to–Multipoint (EuroISDN with MSN) is another type of ISDN terminal interconnection. Here the network terminal (NT) is interconnected with up to eight ISDN terminals through a 4–wire passive bus as shown in the figure below.

2N® TELEKOMUNIKACE a.s., www.2n.cz

2.4 IP Voice Transmission

Speech Encoding Methods

Voice transmission is strictly separated from signalling in VoIP networks. Modern VoIP networks mostly use the RTP (Realtime Transport Protocol) for voice transmission. The purpose of the RTP is only to transmit data (voice) from a source to a destination at real time. Codecs are used to save the channel data capacity. Codecs process the voice signal using variable algorithms to minimise the volume of user data. The degree of compression used by the codec affects the quality of voice transmission. Thus, the better voice transmission is required, the wider data range (the higher transmission rate) is needed. The MOS (Mean Opinion Score) scale is used for rating voice transmission quality, where 1 means the worst and 5 the best quality. For a survey of the codecs supported by 2N® BRI gateway refer to the table below.

	Codecs supported
Standard	Algorithm	Transmission rate	MOS
		[kbps]

G.711a

G.711u

G.729 G.729 is an optional part of the system.

PCM	64	4.1
PCM	64	4.1
CS–ACELP	8	3.92

For 2N® BRI gateway, quadruple the above mentioned rates (two fully duplex calls) and add the TCP and IP header transmission rate to the result to get the resultant transmission rate.

It is important to keep both a stable appropriate transmission rate during connection and a small and identical transmission time per data packet in order to maintain a high–quality voice transmission.

G.711 – this codec is used in digital telephone networks. The PCM (Pulse Code Modulation) is used for voice signal encoding. The sampled signal is encoded in 12 bits and then compressed using a non–linear scheme into the resultant 8 bits. Europe uses the A–law compression system while North America and Japan obey the µ–law. The resultant data flow is 64 kbps.

G.729 – this codec uses the CS–ACELP (Conjugate–Structure Algebraic–Code–Excited Linear–Prediction) algorithm with the resultant transmission rate of 8 kbps. The speech signal is split into blocks of 10 ms each. The parameters of these blocks are then inserted in frames of the size of 10 bytes. 2–byte frames are generated for noise transmission.

During call set–up, a codec is selected automatically for voice transmission. 2N® BRI g ateway supports the codecs included in the table above. The type of codec to be used depends on your VoIP network (individual devices) and your 2N® BRI gateway configuration.2N® BRI gateway is designed primarily for VoIP corporate networks and tries to meet the opponent's codec requirements. If a codec is requested that is incompatible with 2N® BRI Enterprise, the call will be rejected.

The SIP and ITU–T H.323 recommended protocols are mostly used for connection establishing, maintaining and cancelling. 2N® BRI gateway uses the SIP (Session Initiation Protocol) signalling.

2N® TELEKOMUNIKACE a.s., www.2n.cz

Tip

In the case of separated direct connection of your SIP Proxy and 2N® VoiceBlue Next, use the G.711 codec to achieve a high voice quality.

SIP Components

The following components are involved in the SIP message exchange:

UAC (User Agent Client) – the terminal device client, which initiates SIP signalling.

UAS (User Agent Server) – the terminal device server, which responds to SIP signalling from the UAC.

UA (User Agent) – a SIP network terminal (SIP phones, gateways to other networks, etc.), which contains the UAC and UAS.

Proxy server – receives connection requests from the UA and transfers them to the next Proxy server if the given station is not under it administration.

Redirect server – receives connection requests, but, instead of sending them to the called line, sends them back to the requesting device asking for where to route the request.

Location server – receives registration requests from the UA and updates the terminal database accordingly.

All the server components (Proxy, Redirect, Location) are mostly on one physical device called Proxy server, which is responsible for keeping a client database and connection establishing, maintaining and terminating, as well as call routing.

The2N® BRI gateway VoIP–GSM gateway acts as a UA in any case (has the same functions as a VoIP phone), i.e. receives call set–up requirements and, on the basis of its inner LCR table, routes calls to GSM networks.

None of the SIP–defined server components are integrated in the 2N® BRI gateway gateway.

SIP Signalling Messages

Below is a list of messages sent via the SIP:

INVITE – connection set–up request;

ACK – INVITE confirmation by the final message addressee;

BYE – connection termination;

CANCEL – failed connection cancellation;

OPTIONS – server capability query.

The answers to the SIP messages are numerically coded as the case is with the http protocol. Below are the most important ones:

1XX – information messages (100 – trying, 180 – ringing, 183 – progress);

2XX – successful request completion (200 – OK);

3XX – request forwarding needed (302 – temporarily moved, 305 – use Proxy);

4XX – error (403 – forbidden, 486 – busy here);

5XX – server error (500 – Server Internal Error, 501 – not implemented); 6XX – global failure (606 – not acceptable).

2N® TELEKOMUNIKACE a.s., www.2n.cz

2.5 Types of 2N® BRI Enterprise Connection

This subsection deals with the types of connection of the 2N® BRI Enterprise gatewa y to the main ISDN BRI extension.

ISDN TE – 2N® BRI Enterprise Connection

The connection type shown in the figure below provides communication via a GSM/UMTS gateway without PSTN connection. The ISDN telephone sets are connected to the NT port of the GSM gateway, while a mains adapter simulating power supply from the PSTN is connected to the TE port. The adapter is available under Part No. 5020002.

2N® BRI Enterprise Point–to–Point Connection

This type of connection is especially suitable for direct calls from an ISDN branch network to a GSM/UMTS network.

Another possible connection type is NT, where gateway synchronisation is derived from the PSTN BRI extension.

2N® TELEKOMUNIKACE a.s., www.2n.cz

With multiple GSM gateways, the connection lay–out is as follows:

2N® BRI Enterprise Connection as DialThru Router

This type of connection saves one BRI port to the PBX. Incoming PSTN calls are treated by the GSM/UMTS gateway in the DialThru mode while outgoing calls are routed according to the LCR table.

The figure below shows the gateway as a DialThru router for the Point–to–Multipoint extension. Calls are routed automatically into GSM, UMTS or ISDN based on the internal LCR rules.

2N® TELEKOMUNIKACE a.s., www.2n.cz

3. Making Calls via BRI Gateway

This section describes the call routing techniques via an ISDN BRI GSM gateway. The purpose of the settings is to improve your call efficiency and cut your call costs.

Here is what you can find in this section:

3.1 Supported 2N BRI Gateway Functions

3.2 Call Routing Principles

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