Not able to send FAX over SIP Trunk

[mitelnet]

Hi Everyone,
I am a new member, and my experience with 3300 is arround 10 installations...
I am having a problem with My FAX on CXi I.
- SIP trunk with IP phones working perfect.
- Using Codec G711.
- CXi is MCD4.0 SP2
- I have DSPII and compression License in my system (but I am not benificiary from these resources)
- FAX can receive but unable to send

My Fax is connected to ONS port with a etension xxx.
In system speed call: the extension xxx is assigned to number aaa-bbb-cccc. So when you send a fax to aaa-bbb-cccc I can receive the fax at extension xxx.
I replace the fax with an analog standard phone and I was able to make calls.
But the fax always not able to send !!!

Any Ideassss please
Thank you

 

[Mitelpassion]

FAx over IP is always tricky. G711 passthrough is certainly not fool proof and gives problems more often than not.
you should run a packet trace to see where the problem is.

I suggest using T.38 faxing - this requires licenses on the controller.
Else you could use a Linksys 2102 that support T.38 so the end points (fax machine) is repsonsible for negotiating T.38 - this assumes your Service provider for the sip supports T.38 Fax

 

[IrwinMFletcher]

You'll need to be more specific in terms of how the call failed. As mentioned, G711 doesn't guarantee that a fax will work, but given a reasonable network, it should at least get to the negotiation signaling. A trace is the best approach (both SIP signaling and streaming).