Bri hfc <-> avm fritz frame errors


I am trying to connect an avm fritz card in a windows server 2003 to a hfc card in an asterisk box. I am using the AVM drivers for windows and can successfully send and receive faxes in server2003’s fax services. On the asterisk side I have Xorcom rapid 1.1 installed. I have set the card to NET mode with…
insmod {pathto}/zaphfc.ko modes=1
I have set the signalling to pri_net and pri_net_ptmp
I have tried all the span= cas/ccs and h?/ami cominations
I used a xover cable w/o terminators.

I only get framing errors with pri_net and nothing with pri_net_ptmp.

Anyone got any ideas?
Much appreciated.

Ok folks,

I have managed to find out some things.

net_ptmp is the correct mode, with ccs,hdb3 signalling.

When AVM tapi drivers send a fax over the isdn line to the asterisk (zap bristuff) the call is rejected because the requested bearer capacity of audio 3.1k is not supported as asterisk only offers speech.

However if I connect the two devices in cpe mode through a patapsco liberator (a net side isdn simulator 4 bri and 1 pri) the fax is transmitted and received by rxfax to a file on the asterisk box. My conclusion is that the patapsco must convert audio13k to speech capabilities.

All I need now is an ISDN channel that allows for audio13k bearer capabilities.

Also I tried ComISDN VOIP/FOIP TAPI s/w on the 2003 box but hit the t38 passthough problem with chan_sip.
In other words the ComISDN s/w sends a t38 fax and not an analog fax over SIP.

The ComISDN VOIP/FOIP SIP solution would be an ISDN free way of sending Faxes -> Asterisk -> ISDN BRI lines.