hi there, the Mitel is in the UK, and shows caller ID for calls from other people in the UK, but not for calls from outside the UK?
If so, I don't think this is going to be down to settings on the Mitel (but more to whether your phone line provider is sending you the caller ID), assuming the calls that do, and the calls that don't show caller ID, are coming in via the same trunks (ISDN2/ISDN30/SIP)?
Neil.