Sending T.38 Fax over ISDN

[pembajak]

Hello,

I have T.38 fax application that is connected to Mitel 3300 CXi release 9 software using SIP.

That application can receive incoming fax from anywhere including Fax machine that is connected to PSTN.

[T.38 APP] --- Mitel 3300 --- TDM Provider (ISDN /PSTN) ---- Fax Other Party.

However when the app try to send T.38 fax to external fax machine (i.e over provider ISDN), it seems Mitel unable to accept codec change that is initiate from my T.38 Fax app.

Just wondering whether any ever tried to send t.38 fax to external world.
I check the network diagram collect site information from Mitel, they are not mentioning this scenario. Is this something that is not supported?

Thank you.

Best Regards,

Pembajak

 

[IrwinMFletcher]

Yes, it's possible.

Have you tried sending a fax from your app to a physical fax machine off of an analog port on the CXi? Once the fax reaches the 3300, it's now a TDM fax so it won't matter where it goes.

If the SIP call is offered with both audio and T.38 active, the 3300 will switch as soon as it receives a T.38 packet. If it doesn't get one, it will remain in audio mode (G711/G729).

How does your app offer? Have you looked at the SIP signaling?