[SR-Users] bad transport for sips uri?

Hello all, We're having an issue with Kamailio not processing an ACK and hope someone can help. A PCAP shows that Kamailio is receiving the ACK, and we believe these log messages are directly related to it: Feb 21 10:54:01 hostname /sbin/kamailio[15854]: ERROR: tm [ut.h:279]: uri2dst2(): ERROR: uri2dst: bad transport for sips uri: 1 Feb 21 10:54:01 hostname /sbin/kamailio[15854]: ERROR: tm [t_fwd.c:1777]: t_forward_nonack(): ERROR: t_forward_nonack: failure to add branches Feb 21 10:54:01 hostname /sbin/kamailio[15854]: ERROR: sl [sl_funcs.c:387]: sl_reply_error(): ERROR: sl_reply_error used: Unresolvable destination (478/SL) The ACK is as follows. It's from telephone 111111 which is using TLS, which Kamailio listens for on port 5061. Does anyone know which URI has the bad transport as per the error above? Might it be the From URI "sips:111111@es8.example.com" because it doesn't specify port 5061? Thank you in advance. Session Initiation Protocol (ACK) Request-Line: ACK sips:105@70.42.xx.xx:5070 SIP/2.0 Message Header Via: SIP/2.0/TLS 50.78.yy.yy:5061;branch=z9hG4bK741961203 Route: <sips:70.42.xx.xx:5061;transport=tls;r2=on;lr=on> Route: <sips:70.42.xx.xx;r2=on;lr=on> From: ES8 Test 102 <sips:111111@es8.example.com To: <sips:105@es8.example.com:5061>;tag=as7a72b209 Call-ID: 222222(a)50.78.yy.yy CSeq: 94679 ACK Contact: <sips:111111@50.78.yy.yy:5061;transport=tls> Max-Forwards: 70 User-Agent: ewb2bua/15.3.0 Content-Length: 0 -- David Cunningham, Voisonics Limited http://voisonics.com/ USA: +1 213 221 1092 New Zealand: +64 (0)28 2558 3782