SBC Didn’t ACK FAX Core Server 200OK

Guys,

 

We have non-registering SIP Trunk between FAX core server and SBC, and FAX core IP address is session agent in SD with harden port 5060.When someone from PSTN try to call the FAX core number SD send invite to port 5060 and 100 trying/180ringing and 200OK FAX core reply with another port number example 1036 instated of 5060.Is this will cause the SD not ACK to 200OK send by the FAX core? Please advise

 

 PSTN-->SD—>FAX Server(incoming call)

 

Regards

Prakash