Outbound calls always ringing twice

Hello! I’m having a strange issue, and my google-fu isn’t getting very far…

Whenever an extension makes an outbound call through a trunk, it seems to call twice. If I hang up the receiving phone (my mobile in this example), it keeps ringing, then my mobile almost immediately starts ringing again. If I hang up my mobile a second time, the call is terminated.

Also, on the extension initiating the call, you hear ringing twice. This has been outlined in several posts, and I have tried both removing ‘r’ from the Asterisk dial options and made sure ‘Inband Progress’ is set to ‘No’ on the trunks. Neither of these fixes the issue.

I’ve attached a call event log which shows both times I hang up the call on my mobile, and the asterisk logfile can be found here: Asterisk Log - Pastebin.com (different calls but identical symptoms)

Any ideas???