dsl router capabilities for SIP protocol

Posted on 2006-07-14
Medium Priority
Last Modified: 2008-03-17
I'm testing a SIP solution for a client and can barely get beyond first base. An answer to this simple question will help heaps:

Does the DSL Router I'm using (Dlink DSL-G604T) have to specifically support SIP for it to allow pass thru of SIP traffic from LAN clients to public SIP servers? Or is it sufficient to open UDP port 5060? My router was firewall & NAT enabled and port 5060 open for UDP, but registration of the SIP softphone client with the sip server fails. I can telnet to the SIP server on 5060, so something's getting through, but does that demonstrate that SIP should also work? Or do I need a new router?
Question by:ComputerFundi
LVL 36

Assisted Solution

grblades earned 500 total points
ID: 17109839
You should always be able to register but you might get problems with one way audio.
You will probably have to make use of a STUN (proxy) server as this helps to avoid problems with clients behind NAT firewalls.

To register with the server you only need udp port 5060 outbound enabled and by default all outbound traffic is permitted. You only need to specifically permit inbound traffic.
LVL 22

Accepted Solution

Reid Palmeira earned 500 total points
ID: 17127763
you may be having NAT issues. This is one on of the things that devices like Session Border Controllers and STUN proxy servers are designed to help with. What you may want to consider is putting the softphone directly on the WAN link to see if you can register it there (such that it gets a public WAN IP rather than an IP from behind the router. If you can register that way you know it's most likely a NAT/proxy issue.

Author Comment

ID: 17199659
Thanks grblades for reassuring me about the port requirements.
Thanks both for the STUN server NAT traversal info. I've also heard back from the SIP server support confirming that it won't work if NAT is enabled.

I propose to split the points evenly between you.

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