Asterisk and Cisco Router FXO Incoming Call

Cisco routers can be used as a voice gateway for your Asterisk PBX. In this lesson I’ll show you how to configure your Cisco’s FXO port so that it will forward PSTN calls to Asterisk.

Cisco Router

The first thing to do is configure our Cisco router so that it will forward calls from the PSTN to Asterisk through SIP. Let’s start with the voice port:

voice-port 0/3/0
connection plar 500

Now we will create a dial-peer so that the calls are forwarded to Asterisk:

dial-peer voice 500 voip
 destination-pattern 500
 session protocol sipv2
 session target ipv4:<ip of asterisk>
 codec g711alaw
 no vad

This is all you have to do on your Cisco router. Let’s move on to Asterisk…

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Forum Replies

  1. Thank you for sharing. Is it possible to configure the Cisco UC500 to connect to a VOIP GSM gateway (e.g. Portech MV-374)? How to configure it on the Cisco side such that you have four (4) trunks created each presenting a SIM card? If you any idea I will grateful if you can share it.


  2. Hi Roosevelt,

    I wish I could help you but I have no idea. I don’t do a lot of voip…


  3. Hi Rene,

    Can you do a lesson and configuration in connecting a Cisco VoIP system to Asterisk SIP system,
    Im planning to have a lab:

    Branch 1 is using Cisco CUCM or CUCME
    Branch 2 is using Asterisk as thier Voip System

    Can you do a configuration on both Cisco Router and Asterisk to able to connect each other and can call beetwen thier local extension numbers.

    Thanks you.

  4. Hi Jay,

    I’d love to do it some day but right now I don’t have much experience with CUCM or CUCME. I use Asterisk every now and then for some small setups where a Cisco router is used as gateway but that’s pretty much it…


  5. Thanks for the post, is helping me out a great deal.

    I am trying to use a 2621 as a PSTN gateway (2 lines) linked to a Raspberry Pi running FreePBX (Asterisk) but am having a few difficulties.

    What I am trying to achieve is have the 1st line ring a call group (#601) and the second line ring a second call group (#602)

    Also need the PBX extensions to be able to dial out to the PSTN on any available line. The outgoing has some very strange dial plans as is going to be attached to a work internal PBX which can connect to other sites PBX’s (via a 9 dial code) and a

    ... Continue reading in our forum

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