I have a strange issue, with a some kind of complicate architecture…
A router of our internet provider is in front of another bintec rs353j router, at which my freepbx installation is located. However, NAT etc. seems to work fine.
BUT: Something is not working. 
When registering my sip-trunk towards my provider, everything works. Calls are possible. But after some time, when the next REGISTER happens, the answer of my provider is sent towards the wrong port. My freePBX listens on 55060, where the first registration request are answered as they should. in the second registration request wrong ports are used. besides this, Header “Expires” is set to “0” and no “Allows” are listed…
Good case:
2017/02/10 20:40:59.236563 192.193.194.99:55060 -> 217.10.79.9:5060
REGISTER sip:sipgate.de:5060 SIP/2.0
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj7d031cfc-7602-4ac1-a264-bcf8d267500b
From: sip:[email protected];tag=b14c0d37-ef26-4dc5-b112-caf0c12a51f1
To: sip:[email protected]
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2367 REGISTER
Contact: sip:[email protected]:55060
Expires: 300
Allow: OPTIONS, SUBSCRIBE, NOTIFY, PUBLISH, INVITE, ACK, BYE, CANCEL, UPDATE, PRACK, REGISTER, REFER, MESSAGE
Max-Forwards: 70
User-Agent: FPBX-13.0.190.12(13.13.1)
Content-Length: 0
2017/02/10 20:40:59.300873 217.10.79.9:5060 -> 192.193.194.99:55060
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj7d031cfc-7602-4ac1-a264-bcf8d267500b
From: sip:[email protected];tag=b14c0d37-ef26-4dc5-b112-caf0c12a51f1
To: sip:[email protected];tag=86e53dd608d1c001e0b8060625977563.11b6
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2367 REGISTER
WWW-Authenticate: Digest realm=“sipgate.de”, nonce="WJ4Yd1ieF0tFmpj4o617dwQB2X5d9sKR"
Content-Length: 0
2017/02/10 20:40:59.301187 192.193.194.99:55060 -> 217.10.79.9:5060
REGISTER sip:sipgate.de:5060 SIP/2.0
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj5fb9a513-f49b-4823-8c63-6f0a38314d89
From: sip:[email protected];tag=b14c0d37-ef26-4dc5-b112-caf0c12a51f1
To: sip:[email protected]
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2368 REGISTER
Contact: sip:[email protected]:55060
Expires: 300
Allow: OPTIONS, SUBSCRIBE, NOTIFY, PUBLISH, INVITE, ACK, BYE, CANCEL, UPDATE, PRACK, REGISTER, REFER, MESSAGE
Max-Forwards: 70
User-Agent: FPBX-13.0.190.12(13.13.1)
Authorization: Digest username=“custumoerIDe0”, realm=“sipgate.de”, nonce=“WJ4Yd1ieF0tFmpj4o617dwQB2X5d9sKR”, uri=“sip:sipgate.de:5060”, response="1067666a187dd3413fcecede9820e87c"
Content-Length: 0
2017/02/10 20:40:59.367186 217.10.79.9:5060 -> 192.193.194.99:55060
SIP/2.0 200 OK
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj5fb9a513-f49b-4823-8c63-6f0a38314d89
From: sip:[email protected];tag=b14c0d37-ef26-4dc5-b112-caf0c12a51f1
To: sip:[email protected];tag=86e53dd608d1c001e0b8060625977563.262c
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2368 REGISTER
Contact: sip:[email protected]:55060;expires=300
Content-Length: 0
Bad case:
2017/02/10 20:43:08.324919 192.193.194.99:55060 -> 217.10.79.9:5060
REGISTER sip:sipgate.de:5060 SIP/2.0
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj9fb980fb-f4a3-465b-80bd-f25e668b723c
From: sip:[email protected];tag=a5226407-51ae-41c9-845e-4791428aa44f
To: sip:[email protected]
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2369 REGISTER
Contact: sip:[email protected]:55060
Expires: 0
Max-Forwards: 70
User-Agent: FPBX-13.0.190.12(13.13.1)
Content-Length: 0
2017/02/10 20:43:08.387098 217.10.79.9:5060 -> 192.193.194.99:61276
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 99.88.77.66:55060;rport;branch=z9hG4bKPj9fb980fb-f4a3-465b-80bd-f25e668b723c
From: sip:[email protected];tag=a5226407-51ae-41c9-845e-4791428aa44f
To: sip:[email protected];tag=86e53dd608d1c001e0b8060625977563.1e67
Call-ID: 6cf97519-e593-4a7e-bfe4-29141604665d
CSeq: 2369 REGISTER
WWW-Authenticate: Digest realm=“sipgate.de”, nonce="WJ4Y+FieF8wCvpDGuyqz40rHntgzb6xy"
Content-Length: 0
Any suggestions how to fix this?
regards,
andre