Sip read:
REGISTER sip:192.168.1.12 SIP/2.0
To: el eipi<sip:<username>@192.168.1.12>
From: el eipi<sip:<username>@192.168.1.12>;tag=f2104860
Via: SIP/2.0/UDP 192.168.1.11:6108;branch=z9hG4bK-c87542-863262102-1--c87542-;rport
Call-ID: e52cb3325162e56f
CSeq: 1 REGISTER
Contact: <sip:<username>@192.168.1.11:6108>
Expires: 3600
Max-Forwards: 70
Content-Length: 0


11 headers, 0 lines
Using latest request as basis request
Sending to 192.168.1.11 : 6108 (NAT)
Transmitting (NAT):
SIP/2.0 403 Forbidden
Via: SIP/2.0/UDP 192.168.1.11:6108;branch=z9hG4bK-c87542-863262102-1--c87542-;received=192.168.1.11;rport=6108
From: el eipi<sip:<username>@192.168.1.12>;tag=f2104860
To: el eipi<sip:<username>@192.168.1.12>;tag=as774418ad
Call-ID: e52cb3325162e56f
CSeq: 1 REGISTER
User-Agent: Asterisk PBX
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER
Contact: <sip:<username>@192.168.1.12>
Content-Length: 0


 to 192.168.1.11:6108
Feb 27 19:29:34 NOTICE[22787]: chan_sip.c:8418 handle_request: Registration from
 'el eipi<sip:<username>@192.168.1.12>' failed for '192.168.1.11'