Extend POTS line via FXS/FXO cards?

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Jun 1st, 2011
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We have a remote site with IP connectivity.  At a more-local site we have a POTS line for Fax, which we would like to extend to the remote site.  I've searched for config examples but keep coming up empty, which leads me to believe this isn't possible...

           ---------------          ---------------

POTS ------| FXO  | WAN  |          | WAN  | FXS  |------ FAX

LINE       | PORT | PORT |----------| PORT | PORT |       MACHINE

           ---------------          ---------------

                           MORE LOCAL               REMOTE

                                 ROUTER                  ROUTER

Unfortunatly we are not a Call Manager shop, but we were gifted a couple of 2600's with FXS and FXO cards during a building acqusition, so we have that going for us.

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Nizar Abuseni Wed, 06/01/2011 - 16:39
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I have done this before with no issue's, maybe my use was little bit different but same concept. My call flow was as follow:

PSTN ----- FXO----VGW 1--------------- VOIP ------------VG2 --------FXS-------PBX

where is you problem? what configuration you have done?

rrfield Thu, 06/02/2011 - 05:52
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Thanks for the reply.

I haven't done any config, I was looking for some examples first...but have not found any. 

The hardware I have available are two 2610XM routers, one with an FXS card, one with an FXO card.

Also, this is PBX-free, simply a POTS line extension.  I know there are other devices I could purchase to complete this task, but though I'd try to recycle some gifted hardware.

Nizar Abuseni Thu, 06/02/2011 - 12:24
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I think i had a document which contained example.

Also i can share with you a sample config if you want.

Best regards,


Sent from Cisco Technical Support iPhone App

Nizar Abuseni Mon, 06/06/2011 - 14:44
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Sorry for late reply.

You can check "Configure the Cisco 2651 Router" section in the below link:


This is one side FXO/FXS only, but if you have both sides or many sides its same concept.

you will use POTS dial-peer to go out through FXO, and you will use VOIP dial-peer through cisco gateways.

Let me know if that will help you.

Best regards,


rrfield Tue, 06/07/2011 - 18:08
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hey thanks a lot!  I am out of town the next few days but will get this set up as soon as possible!


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