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New Member

Cisco off ramp Fax!!

Hi all,

wondering if anyone can shead some light on this for me;

Bascially my problem is as follows;

I'd like to configure a Router to run T.37 store and forward Fax off Ramp gateway, so that a Router can recieve an email and somehow determine the destination phone number to send on a Fax over PSTN using intenal Modems or Voice ports. Ideally I'd like to have a list of 100 different destinations so that on receipt of an email a specific destination Fax number can be selected. How does the Router determine the destination Fax number from the email recieved? Is My idea at all possible, is there any configurations out there? I've read the Cisco Articles at

but it hasn't been that clear on how to determine the destination fax string from the recieved email.

Thanks very much for your time.



Cisco Employee

Re: Cisco off ramp Fax!!

Hi Paul,

I am not sure if i understand the part of 100 different destination, so I will let you explain that in further detail. To answer your question about how router determine the destination fax number from recived email is the users will send fax with following format FAX=5555555@ or for this cofiguration you will need DNS entry in your SMTP server. In both of this cases router will extract 5555555 from the recevied email and send call out to voice-port. Also it will convert TIFF-F and convert it to fax.

Hope that helps..


New Member

Re: Cisco off ramp Fax!!


thanks for your replay. What I meant by having 100 destinations is that I'd have, if possible, 100 dialer peer entries with the destination pattern of each fax number to call. What I understand from your post is that the Router will extract the fax number from the email no matter what the number is without the need for dialer peers, is this correct? Is there any configurations out there that might help? I have a network diagram I could email to you if I'm still not making myself clear.

Thanks again,


New Member

Re: Cisco off ramp Fax!!

Hi, you may be able to help me with understanding how this all c

omes together. When sending

how does the SMTP server know to relay this address to the router?

Thanks for yoiur help.

New Member

Re: Cisco off ramp Fax!!

Hi, because the SMTP server uses the DNS service, and the DNS server solves the to a particular IP Address, which is your Router´s address.

New Member

Re: Cisco off ramp Fax!!

Hi, we had T.37 working fine from both MFD and MAPI client, however...

Not sure if this relates to your business, but we could no longer use the service as our users were not able to receive a confirmation that a fax had been received by the recipient. This was due to T.37 using syncrohnous T.30 protocol for talking to end points. I know T.38 is a asynchronous protocol that would work for us, but this mean purchasing a third party application to sit in between client and the voice gateway.

Did you find a way around this behaviour?