[OpenSIPS-Users] OpenSIPS FreeSWITCH TCP support

[Matthias Kneer]

Hello,

I'm using OpenSIPS as a loadbalancer / failover proxy and mid registrar 
in AOR mode, also for doing the NAT keepalives, in front of 2 FreeSWITCHes.

While using UDP everything works fine. Since I now want to implement 
TLS, I first started to test TCP to have the baseline working to go on 
with TLS afterwards. Unfortunately, while using TCP, none of TCP 
registered phones receives inbound calls - while outbound calls from 
these phones to other UDP registered phones work without an issue. The 
registration seems to work fine and also the information in the 
userlocation of OpenSIPS properly recognizing the registration over TCP:
# opensipsctl ul show
Domain:: location hash_size=512
         AOR:: 212 at sip.example.org
                 Contact:: 
sip:212@[EXTERNAL_PHONE_IP]:40009;transport=TCP;rinstance=ebc7149013d15489 
Q=
                         ContactID:: 1156589880790491998
                         Expires:: 18
                         Callid:: Y6nJ2r4Iwm6WNL_KHqcLOQ..
                         Cseq:: 2
                         User-agent:: Zoiper rv2.9.2
                         Received:: 
sip:[EXTERNAL_PHONE_IP]:40009;transport=tcp
                         State:: CS_SYNC
                         Flags:: 0
                         Cflags::
                         Socket:: tcp:[OPENSIPS_IP]:5060
                         Methods:: 5951

It looks like FreeSWITCH is not recognizing that the phones are 
registered through TCP even though the packets seem to contain the 
required information. Here's a dump of a the registration through TCP 
taken from the FreeSWITCH: https://pastebin.com/mbMffLK7


And here's the output of the active registrations on the FreeSWITCH for 
the above mentioned phone, which also contains the transport information 
in the contact header:

Call-ID:        Y6nJ2r4Iwm6WNL_KHqcLOQ..
User:           212 at sip.example.org
Contact:        "212 ZoIPer" 
<sip:212@[OPENSIPS_IP]:5060;ctid=1156589880790491998;fs_path=sip%3A[OPENSIPS_IP]%3Btransport%3Dtcp%3Blr>
Agent:          Zoiper rv2.9.2
Status:         Registered(UDP)(unknown) EXP(2019-07-22 18:02:32) 
EXPSECS(131)
Ping-Status:    Reachable
Ping-Time:      0.00
Host:           freeswitch
IP:             [OPENSIPS_IP]
Port:           51540
Auth-User:      212
Auth-Realm:     sip.example.org
MWI-Account:    212 at sip.example.org

Could someone guide me, at which point I do have to handle TCP different 
from UDP? I'm pretty new to this whole VoIP / SIP topic.

Thanks in advance,
Matthias