SIP/2.0 400 Illegal 14. header line, no colon

[Cetartiodactyla]

I’m can register to the SIP Server but fail to make a call. It says header line, no colon

15:14:17.544 pjsua_core.c .RX 390 bytes Response msg 400/INVITE/cseq=7079 (rdata0x7fa9e0074c28) from UDP XX.XXX.XXX.XX:5060:
SIP/2.0 400 Illegal 14. header line, no colon
Via: SIP/2.0/UDP 192.168.0.12:54895;rport;branch=z9hG4bKPjkIxAf-bnJtM0-0.y6NexBUaaFfpJJkp.
From: "012345678901" sip:[email protected];tag=gkXeu.oMIuKLY5lmZKTvNRsXhV.0acQq
To: sip:[email protected];tag=badrequest
Call-ID: mPY0Lh6tK2pcZ8MxgBzfIPeZ3PBfuSEw
CSeq: 7079 INVITE
User-Agent: FRITZ!OS
Content-Length: 0

[olku]

I don't see what points to Telephone causing this. You're posting the server response to the invite but did you also log the sent invite?

Capture a network trace on the device running Telephone and do the same on the SIP server. Compare the two traces. My bet is that there's absolutely nothing wrong with the initial invite sent.

Your router probably employs SIP ALG which rewrites (and corrupts) the SIP header causing the call to fail. Forementioned missing colon in header parameters is a known-issue with SIP ALG. Proper logging on both ends will show.