Clicking on some asterisk sip calls


I have asterisk running on the following hardware and I’m getting a clicking sound on some calls:
You can hear an except from a call here:

Xeon 3.4
3GB Memory
2 x Intel Pro1000 NIC
FreeBSD 8.1 i386

The server is connected to a cisco switch, then to a cisco router with a 100mb fibre leased line on the back of it. There is currently no QOS on the switch or router.

Calls all come in via SIP (alaw or ulaw) and we are using both Sipgate and Draytel.

The strange thing is, it only happens on certain calls. We have some customers whose calls we can guarantee will always be terrible. However, I am completely unable to replicate the problem myself as call quality is always fine from every mobile phone or landline I can get my hands on, regardless of how many times I test it.

We have changed the server hardware (only the HDD is the same) and the sip provider but still get the problem. I’ve also moved from asterisk 1.4 to

I’ve spent a long time trying to find an answer to this and haven’t really got anywhere so I would be interested if anyone here has seen a similar problem or has any ideas.


Sounds terrible. Are your customers also using SIP ? I suggest to try and record the audio when it enters your VoIP network before it passes any handling.