I have an Asterisk server on a public IP address. I am using the N900 SIP client to connect as an extension. Everything works over WiFi but registration drops after a couple of minutes over tmobile 3g, i.e. asterisk doesn't see the extension as online anymore and calls go to voicemail.


If I get on the phone as root and put the phone in a continuous ping to anywhere on the internet, registration stays on for like 20 minutes before dropping.

Any ideas?

BTW no problem keeping skype registered at all tymes

What's the SIP user like?

Could be a few things but if your T-Mobile connection is like mine your assigned an RFC1918 address and NATed to the Internet. It's quite likely that your having NAT issues or even that the IP on your phone is switching at times.

You should look at using a STUN server or other proxy but you can play around with a few things:

- Try adjusting the registration time on the phone to less than 5 minutes.
- Try adding qualify to the configuration if you don't have that already. This will force keep alives to help with NAT timeout issues.
- Make sure the phone is configured with NAT=YES if it isn't already.

Good luck -

I had this same problem using t-mobile's internet3 APN (VPN data plan) which gives a routable (but firewalled) IP address. I was able to get this to work by adding this to my extensions.conf for my phone:

qualify=5000
qualifyfreq=30

I use 5 seconds for the qualify timeout because I got tired of seeing in my logs that the phone was lagged. The change in frequency is needed since if the packet is lost, the sip udp connection could timeout which appears to be the cause of the problem.

I have the same problem

If you're using asterisk and can make changes to it, try the settings I posted above your post. It works for me.

Yeah. I do exactly that... Note that I prefer to not monitor 3G extension. What keepalive method are you using? options or register?

I've tried a lot of different configuration and still with this problem.

After some time the extension come not available.

The qualify parameters isn't working great with me. Anyone else is passing for this same problem?