Configuring voice service on a Cisco 2801 Integrated Services Router via Asterisk

So I’ve configured voice service a number of times, but never using Cisco equipment. There’s a business starting up here on Orcas Island and they need a number of lines voice and fax service. I had a spare 2801 router laying around and heard that it’s possible to provision voice service using these machines. So I looked on eBay for a module that will provide more than two FXS ports and decided on the VIC-4FXS. When it was delivered, I installed it and booted the router. It told me that it needed a PVDM DSP Module, so I got one of those as well. It has arrived. I have installed it. Now when I boot the router, I don’t get a warning or an error.

configure the router to send outbound calls to the SIP server

configure the router to send inbound calls to FXS ports 2,3,4 in round robin

trunk group FXSlines
voice-port 0/2/1
 trunk-group FXSlines
voice-port 0/2/2
 trunk-group FXSlines
voice-port 0/2/3
 trunk-group FXSlines

configure the router to send inbound calls to the correct ports on the VIC-4FXS

dial-peer voice 1 pots
 preference 7
 destination-pattern 3602987792
 translate-outgoing called 10
 port 0/2/0
 forward-digits all
dial-peer voice 2 pots
 preference 2
 destination-pattern 3602987793
 translate-outgoing called 10
 port 0/2/1
 forward-digits all
dial-peer voice 3 pots
 preference 3
 destination-pattern 3602987794
 translate-outgoing called 10
 port 0/2/2
 forward-digits all
dial-peer voice 4 pots
 preference 4
 destination-pattern 3602987795
 translate-outgoing called 10
 port 0/2/3
 forward-digits all

configure the router to accept inbound calls from the asterisk call server

voice service voip
 allow-connections sip to sip
 no supplementary-service sip moved-temporarily
 no supplementary-service sip refer
 fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback cisco
  registrar server expires max 3600 min 3600
  localhost dns:

configure the asterisk call server to send inbound calls to the router

On asterisk call server, edit sip.conf to register with SIP server on cisco router at


On asterisk call server, edit extensions.conf and add extensions to the incoming context:

exten => 3602987792,1,Dial(SIP/fhvoice/${EXTEN},30)
   same => n,Hangup()

exten => 3602987793,1,Dial(SIP/fhvoice/${EXTEN},30)
   same => n,Hangup()

exten => 3602987794,1,Dial(SIP/fhvoice/${EXTEN},30)
   same => n,Hangup()

exten => 3602987795,1,Dial(SIP/fhvoice/${EXTEN},30)
   same => n,Hangup()

configure the asterisk call server to accept outbound calls from the router

2 responses to “Configuring voice service on a Cisco 2801 Integrated Services Router via Asterisk”

    • Only enough to know that I don’t know enough about ios, unfortunately. I tried but didn’t have enough tuits and they were getting expensive. I have the hardware in case I want to give it another go, though!

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