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New Member

T.37 Store and forward fax

I use a Cisco 2621XM Router with 12.3(11)T6 IOS, NM-HD-2V with VIC2-2FXS and I try to configure the t.37 protocol. Olso, I use a smtp Exchange server for a fax mail server and a fax machine connected in a FXS port. I use the Cisco Configuring documentation in the configuration process, but I have a problem: after I configured the FXS pots and after I use the "call application on-ramp " I receive the busy tone when I peek up the phone and I can't send a fax msg. The question is: What are be the problem for this busy ton?

New Member

Re: T.37 Store and forward fax

Hi. It seems as if the on-ramp fax application was designed to be used only with digital interfaces, such as E1 or T1. This is because the router needs to receive a DNIS in order to match the inbound dial-peer where the application is configured. Because analog interfaces do not carry a DNIS, the on-ramp application will fail.

In order to be able to use this application with an analog interfaces, such as your FXS, you need to do a trick. You need to configure a translation profile that will assign a DNIS to your inbound call, and will allow the inbound dial-peer to be matched.

In this sample configuration, voice-port 3/1/3 is your FXS port whre the fax machine is attached and is the mailbox where you want your fax to be delivered. Don't forget the required mta send commands.


voice translation-rule 3

rule 1 /^$/ /7777/



voice translation-profile DNIS-Replace

translate called 3

voice-port 3/1/3

translation-profile incoming DNIS-Replace

caller-id enable

dial-peer voice 7777 pots

application on-ramp-fax

incoming called-number 7777


port 3/1/3


dial-peer voice 7778 mmoip

application fax_on_vfc_onramp_app out-bound

destination-pattern 7777

information-type fax

session target

Good luck!!

Rafael Campos

New Member

Re: T.37 Store and forward fax

Busy tone is still present, but c2621 report to me this mess:

%LAPP_ON_MSGS-6-LAPP_ON_CAUSE_NO_MEMORY: No memory available

Memory requirement for confuguration t.37 on c2600 is 48 MB DRAM ( and i have 128. Which reason for this mess?

New Member

Re: T.37 Store and forward fax

After installing one more 128 MB memory module, error mess, that originated earlier, no more appeared and fax is outgoing to SMTP server. What reason for this requirement and how i can using t.37 with 128 MB memory module? Most of gateways, that i have, shipping with smaller amount of RAM and i prefer getting by without install additional memory. That is very difficult.

New Member

Re: T.37 Store and forward fax


I had the same problem, and with the answer from Rafael, it worked.. but..

If i have not only one mmoip fax to forward the fax to, but some mmoip faxes, needing to match and distinguish (some faxe numbers mean different emails, meaning different matches)? (so i cant use always the same DNIS, from the rule)

Any hint Rafael?

New Member

Re: T.37 Store and forward fax

Unfortunately, due to the very nature of the FXO port, which lacks for DNIS information, you can't do that. If you need incoming faxes to be sent to different e-mail accounts you'll need to have several FXO ports, one for each possible destination.

It's basically the same reason why you can't have DID in analog ports.



New Member

Re: T.37 Store and forward fax

But, ive got just one fax in a FXS port. I just want to be able to send to different mmoip faxes from this analog machine. Isnt that possible? (with the rule from your explanation it always send to the same).

Did you understand the question?

Thanks :)


New Member

Re: T.37 Store and forward fax


I tested it and it works. Try use this configuration:

! define fax's number and start fax onramp app

! when port goes offhook

dial-peer voice 10 pots

! common fax onramp app

service fax-on

destination-pattern 30

! fax in FXS voice-port 0/0/0

port 0/0/0

! incoming (from fax to T.37)

dial-peer voice 20 mmoip

service fax_on_vfc_onramp_app out-bound

! any number will match

destination-pattern .T

information-type fax

session target mailto:...

! optional DP for faxes from T.37 to fax

! outgoing (from T.37 to fax)

dial-peer voice 30 mmoip

service fax-off

information-type fax

incoming called-number .T

In this case fax sent to any number will be catched by T.37 application and sent to mailto: address.

When you will sent T.37 email to gateway with called number 30, it will reach fax on 0/0/0.

When you want to sent T.37 email to different numbers and lines, you have to define more POTS DPs.

In configuration above FXS port 0/0/0 can't be used for phone. Any call made by this phone will be treated as fax independently on dialed number.

And one more note: when you use FXS (or FXO) with this setup, all faxes have to be handled by T.37. No fax from that port will be processed by POTS - so you can't send some faxes to T.37 and some to E1 link (for example).

Jirka Novak

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