Phone registers, but can't call out. Inbound rings, no voice


I’m a bit of a VoIP noob. I’ve done some reading and believe I understand the concepts involved, but I still can’t figure this one out. I’m trying to get multiple voip phones at our new office working. I’ve setup phones at satellite offices before without a problem, but this one just isn’t playing nice. I am an IT guy, so please be as technical as possible. Thanks in advance for the help.

The Setup:

The asterisk server is public on the Internet (ie: no NAT), and firewalled (iptables). I have two voip phones (snom brand) on a private network (ie, behind a router, thus NAT’d). (The router is a dlink, if you need to know the firmware I can find out).

The Symptoms:

The phone registers with asterisk just fine. However, the phone will ring for an incoming call, but when picked up, there’s no audio. Outgoing calls don’t work at all.

The Details:

When examining the sip log on the phone, I can see that the register sequence completes. When I dial out, I can see that an INVITE request packet is sent, but no response pack is received. From what I understand, the phone should get an acknowledgement packet from the asterisk server. Monitoring the server (using #asterisk -r) I see no indication that asterisk has received the INVITE request (debug level at 3).

The sip.conf for the extension does have a ‘nat=route’ directive, and the firewall does allow the sip traffic (udp 5060) for the public ip of the private network.

The router does have a ‘SIP aware’ option which is enabled (disabling this prevented the phone from even registering).

This is the first time I’ve seen things half working. Every other time, once the phone registered, it worked.

Any pointers how to further debug the problem is greatly appreciated.


What version of Asterisk are you using? nat=route isn’t an option for 1.8: no, force_rport, yes, comedia.


I’m using Asterisk However, I’m pretty sure asterisk is not my problem as it’s worked just fine with every other setup.

– Actually, I just checked the router and the firmware was pretty old. Reading more, I found out VoIP wasn’t supported on that version. I upgraded the router firmware and everything works fine.

Thanks for the help, totally pointed me in the right direction.

Glad it worked, still curious, but not that curious. :smile: