Dailplan problem


I’m having problems with the voip of one of our customers.

The dialplan has worked for several years now, until yesterday.
Outgoing calls work perfectly, but when someone tries to call them, it takes a few seconds before Asterisk grabs the call and sends it to the right sip account. Also the sound file (which worked fine until now) is distorted. Just to top things off, after 2 rings on their telephone it goes straight to voicemail.

I’ve tried changing things in extensions.conf. But no matter what changes I make, after a dailplan reload, nothing changes.
i.e. I deleted the voicemail command in extensions.conf, it still goes to voicemail…

Restarting asterisk worked for a few hours, than the server went down, after restarting the server, just to same problem.

Anyone any idea what it could be ?

(PS: I’ve changed the config to another server, and it still has the same problems…)