Got an issue today with calls from Spark SIP, Mobile and Analogue Lines to a Vodafone SIP trunk with a Fax Server. The RTP to the Vodafone SIP trunk stops after a second immediately after a "PT=Comfort noise" packet from Spark, from what I see on my wireshark capture. I have tested from Vodafone and 2Degrees mobiles and I don't get the same issue. This was not happening prior to today and does not happen to voice calls on the same trunk.
Does anyone know about any changes within the Spark Voice platform that could have this effect on the fax calls? It's like they are auto detecting the fax an implementing a suppression feature.