Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Help with T.38 Fax over SIP Trunk

I have a UC520 (CME) system connected to PSTN via a SIP trunk provider. The SIP trunk supports T.38 faxing.

I have a fax server setup with StoneFax to terminate the faxes. I have setup an incoming dialpeer with one of my DIDs. upon sending a fax, the line rings once, then seems to connect, but it is just dead silence. The microsoft fax service on the fax server shows 'answering' but nothing ever happens.

I am mostly concerned about my dial-peer config.

Here is the dialpeer config that StoneFax suggests:

dial-peer voice 20 voip

description INCOMING FAX FROM PSTN TO STONEFAX

destination-pattern <<DID HERE>>

session target ipv4:<<FAX SERVER IP>>:1721

dtmf-relay h245-alphanumeric

codec g711alaw

fax rate 14400

fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback cisco

no vad

should this work ok over a SIP trunk? are there any other system settings i should change? I am wondering about the DTMF settings. Cisco configs usually show h245-signal, and all my voice dialpeers are rtp-nte.

1 REPLY
New Member

Re: Help with T.38 Fax over SIP Trunk

Also one followup question, how do i create an outgoing dial-peer to be used for sending outgoing faxes, and lock it down so that ONLY the fax server uses it? i currently have several outgoing voice dialpeers setup with COR lists for call restrictions, so i want to give the fax it's own dial-peer, but make sure that none of the voice callers use it.

409
Views
0
Helpful
1
Replies
CreatePlease to create content