LinkSys PAP2T: problem with sending fax

HOLGER HAHN · ‎06-21-2010

We got a LinkSys PAP2T to connect analog fax machines to our Cisco CUCM 7.1.

In several forums and communities I found a lot of information to configure the PAP2T. (Jitter, Codec, Passthrough Methode, etc.)

But as in other threats I have the same problem with sending faxes.

Receiving faxs works fine and sending to our Ferrari Fax Server too. But sending faxes to other "real" fax machines fails.

The receiving machine goes offhook and they try to connect (you can hear the modem tones) but connection fails.

As I said, the PAP2T is connected to our Cisco CUCM as a SIP client. The connection to the outer world goes via a Cisco 2821 router as a voice gateway. The Ferrari Fax Server is connectet to our old PBX in the same manner as our old fax machines, and the PBX is connected to the 2821 gateway. So the connection to the fax server is the same as to our fax machines.

I tried with g711alaw and g711ulaw but send to fax machines doesn't work.

I the dial-peer in the gateway I set codec an fax pass-through to the same codec as in the PAP2T.

Can anbody tell me what I can configure to make sending faxes work?

Thanks.

sabah1000 · ‎06-21-2010

Dear Holger,

Not that I am very experienced with your exact setup, but I think there are at least two factors that affect FAX operation.

The first you have already ruled out, that is the use of High bandwidh codec, G711.

The second, which is likely the reason in your case, is to force your fax to a lower speed fax like 9600bps instead of the 19200bps.

I have noticed that many fax machines cannot handshake on 19200bps.

Good luck.

Sabah

HOLGER HAHN · ‎06-21-2010

Sorry, but it don't work.

Lowering the speed to 9600bps (V.29) takes no effect.

I teted it with different machines.

I think I have to buy another ATA like the SPA2102 which supports T.38.