FAXing out over PRI

Unanswered Question
May 2nd, 2008

I plan to connect a FAX to an FXS port on a UC520 that uses PRI for PSTN access. Our current telcom provider thinks that FAXes over PRI will not work too well or maybe not at all. Any truth to this? What about inbound? Any problem there?



I have this problem too.
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Kenneth Mohammed Fri, 05/02/2008 - 11:34

I have several customers who fax over a PRI, and I havent heard any major issues. You may have to tweak the configuration to get it to work correctly, but as far as I know, it works fine.

hassan_oudeh Tue, 05/13/2008 - 02:16


I have a small problem with my FAX machine which is connected to FSX port.

The call flow is :

PSTN --E1--> 2811-GW --FXS--> Fax Machine

The problem is unpredictable as sometime the fax works perfectly (sending and receiving) and sometimes it will be cutted means that only half of the page can be send/receive and the rest are blank !!

any idea please ?


Paolo Bevilacqua Tue, 05/13/2008 - 02:58

Please check for slips with "show controllers e1" and add the network-clock-participate and -select commands.

Hope this helps, please rate post if it does!

hassan_oudeh Tue, 05/13/2008 - 03:03

i alreday did it. but still the same !

how i troublshoot this issue, debug or somthing !?


3dtgnt_ljm Tue, 05/20/2008 - 00:10

I have the same problem ! Is there someone can told me how can I do ? thanks

Paolo Bevilacqua Tue, 05/20/2008 - 02:14

Whta problem exactly do you have and what type of lines, and how you faxes are connected.

hassan_oudeh Tue, 05/20/2008 - 02:24

fax machine is connected to FXS port on the router. it have a DID number taken from E1 line on the same router.

so the call fllow PSTN->E1 POTS->FXS POTS

The probelm is when sending.reciving the faxs it's not complete, i.e. if the original page was:






will recive the fax link this:





it's un-predictable behavoir !

im not able to know how we can dubug or fix it !

any help will be appreciated please....



wbarren Tue, 05/20/2008 - 07:18

We use CME on a 2811 and are faxing using an ATA and experienced the same issue. Turns out when we disabled the "G3" feature on the fax machine it fixed everything. We also use this setup through an FXS port without issue.

Paolo Bevilacqua Tue, 05/20/2008 - 07:21

Likely you do not have network-clock-participate and network-clock-select commands for this circuit. Result are slips that you can see with "show controllers E1". Configure said commands and problme will be resolved.

Hope this helps, please rate post if it does!


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