SIP Trunk behind a NATed router

[twhittle1]

Hi,

Is it possible to use a SIP trunk to a SIP ITSP provider having the CUBE / gateway router behind a NATed firewall?

Has anyone done this?

I'm asking because I'm having problems getting my SIP trunk to work and my cube router is behind my generic service provider router, which is doing the NAT. I just want to rule this out as a problem.

Has anyone else done this? Or is it actually not possible?

Many Thanks,

Tom

[Jitender Bhandari · Accepted solution]

Hi,

As long as NAT is working fine SIP would work properly as protocol.

Below is the RFC for "NAT Traversal Practices for Client-Server SIP"

https://tools.ietf.org/html/rfc6314

HTH

JB

[Jitender Bhandari]

Also see below.

http://www.voip-info.org/wiki/view/NAT+and+VOIP

http://www.linuxjournal.com/article/9399

http://kb.smartvox.co.uk/voip-sip/sip-nat-problem/

JB

[Dennis Mink · Accepted solution]

Yes its possible, but not always easy to set. theoretically port 5060 and 5061 needs forwarding to your CUBE and in addition, RTP ports that get dynamically assigned withing the SIP signalling.

Cisco VCS-e deployment is based on this, and yes works, most definitely. 

however, you cant rule out that the service provider router is the issue. 

you might want to add some sip debugging off of your CUBE to this post if it isnt working

[twhittle1]

Many Thanks Both, I'm going to proceed then and just be a little careful.

Thanks,

Tom

[Jitender Bhandari]

Happy to help,

Most of the problem i have seen with NAT is with SDP, either IP\Port not being sent correctly or not being sent at all. Keep that at the back of your mind.

HTH

JB