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New Member

Fax over IP... confused!

Hi guys,

I'm very confused about how fax relay works in a Cisco VoIP environment. I've read all the documents I could find, but questions remains.

Do I have to apply the directives on a dial-peer with the destination-pattern set as the fax extension number ?

Or does the system automatically detects if the call is a voice call or a fax call ?

In fact, I don't quite understand how I can define what devices should use fax relay (cisco protocol, not t38)

Here's an example of what I've done so far.

37002 is the extension number of a fax in a remote office.

dial-peer voice 37002 voip

destination-pattern 37002

fax-relay ecm disable

fax-relay sg3-to-g3

fax protocol cisco

Is that right ?

Thanks !


Re: Fax over IP... confused!

you may want to add the ip address of the remote gateway you are sending to under the dial-peer

session target ipv4: [ip address of remote gateway]

New Member

Re: Fax over IP... confused!


The dial-peer not detected which device delivery the call

You have insert the destination for each device

for example:

dial-peer voice 1234 voip

destination-pattern 1234

session target ipv4:


dial-peer voice 1234 pots

destination-pattern 1234

voice-port 0/0/0

do you understand?

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