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Hello, I'm testing T38 for my service provider.


My information technology is: I have a PBX MD110 connected to a GW (Cisco or Teldat) , I have to configure the GW with dial-peers voice pots and sip for routing the inbound calls for the PBX and the inbound calls of the NGN Network.

I´m testing fax T38 now, and i send faxes from my PBX to NGN Network by SIP correctly but i don´t receive faxes to the fax of the PBX from NGN Network


I have two PCs with software called VentaFax & Voice which simulate two FAXs


I have captured with Wireshark:


TrazaFAX is a bad trace, from fax out of my PBX to fax of my PBX. The fax call falls because i think the fax out my PBX doesn´t transmit anything


I´m in Europe , i changed the codec to G711alaw (although the trace is with G711ulaw) , and i also changed the PCs from one extreme to the other just in case the problem was the modem of the PC


Can anybody help me with the call trace?




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My Fax send an image in a call through my PBX , this call goes to my Gw through primary ISDN, the GW has a SIP SERVER ( and signals against a SIP SERVER of the NGN Network ( and routes the call with T.38. In this sense , the call is OK and i receive the FAX in the other side but when the call is originated by the fax of the NGN Network, i see the call in my GW and i see that two faxes comunicate but however the ouside fax don´t transmit the image. Monday, i can send you the good trace in sense PBX- outside

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