Problems with AAstra / Mitel 6863i Revision 0

Hey Guys,

Not had to ask for help before, but need some now.
Freepbx 12.0.43

The pbx is hosted in a Datacenter, with a SSL tunnel connecting the site.
Phones connect fine, and inbound and outbound calls can be made.
Problem - On boot of a phone (Or a phone idle for 20 or so minutes) if you attempt to dial out or internal, the second line on the phone rings with the users phone number.

If you hang up on both lines, then re dial the number it works fine.

I cannot find anything on the logs to give me a clue - Any ideas ? Please