
P-870MH-C1
VDSL Modem Over POTS
Quick Start Guide
Version 3.50
12/2006 
Edition 1
Copyright © 2006. All rights reserved.

P-870MH-C1 Quick Start Guide
Introduction
The P-870MH-C1 is a VDSL modem with a four-port switch. 
VDSL offers high-speed Internet access. The four-port switch 
lets you connect up to four computers to the P-870MH-C1.
Refer to the User’s Guide for detailed information. 
1 Hardware Connections 
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1DSL: Use a telephone wire to connect this port to a 
telephone wall jack for Internet access.
2ETHERNET: Use an Ethernet cable to connect a port to a 
computer for Internet access. 
3POWER: Use only the included power adaptor to connect 
this socket to an appropriate power source. Press the 
button to turn on the P-870MH-C1. 
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P-870MH-C1 Quick Start Guide
1.1 Check the LEDs (Lights)
•The POWER LED blinks and turns steady on. 
•The VDSL and/or ETHERNET LEDs turn on and sometimes  
blink if the corresponding ports are properly connected.
V If none of the LEDs are on, unplug the device 
and check your hardware connections again. 
2 Test Your Internet Connection
After you have connected the hardware and turned on the P870MH-C1, open a web browser on your computer and go to 
any web site (for example, www.zyxel.com) to test your 
Internet connection. 
Troubleshooting
1 The POWER light is not on when I turn on the P-870MH-
C1.
• You might be using the wrong power adaptor. Use the 
included power adaptor only.
• If you are using the correct power adaptor, disconnect 
and re-connect the power adaptor, and turn on the P870MH-C1 again.
• If the POWER light is still not on, use a different power 
outlet. Make sure the power source is also turned on. 
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P-870MH-C1 Quick Start Guide
• If the problem continues, contact your local vendor. 
2 The ALARM light is on.
• The ALARM light blinks once during system startup. If 
the ALARM light stays on, the system startup test has 
failed on your P-870MH-C1. Contact your local vendor.
3 The POWER light is on, and the ALARM light is off, but the 
VDSL light is blinking slowly.
• Check the connection from the DSL port to the telephone jack.
• Connect the DSL port to a different telephone jack.
• Make sure VDSL service is activated for the telephone 
jack.
• If the problem continues, contact your DSL service 
provider.
4 The POWER light is on and the ALARM light is off, but the 
ETHERNET light(s) is also off.
• The ETHERNET light is off if you have not connected a 
computer to that port.
• Check the Ethernet connection between the ETHER- 
NET port and computer.
• If the connection is secure, inspect the Ethernet cable 
for damage.
• If the Ethernet cable does not appear to be damaged, 
check the length of the cable. Ethernet cables must be 
less than 100 meters.
5 I cannot connect to the Internet.
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P-870MH-C1 Quick Start Guide
• There might be problems with your VDSL settings or 
phone line. Contact your Internet Service Provider 
(ISP) and/or telephone company. 
Procedure to View a Product’s Certification(s)
1 Go to www.zyxel.com.
2 Select your product from the drop-down list box on 
the ZyXEL home page to go to that product's page.
3 Select the certification you wish to view from this 
page.
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