The 2 extensions are on 2 IP phones. If i'm not available and reachable on my mobile phone i want to use the specific trunk to call me on my mobile so i can see on which trunk the customer calls me and i know how to answer my phone.
example:
Trunk 1234 calls extension 1234 <not available > forward to extension mobile 1234 using outbount trunk 1234
Trunk 5678 calls extension 5678 <not available > forward to extension mobile 5678 using outbount trunk 5678
If you expect any call to your mobile phone which will reach it via a PSTN trunk, to somehow indicate which trunk it used, other than with CallerID, you are out of luck.
But please restate your example with the relevant extension numbers, trunk names and telephone numbers, so what you are trying to achieve becomes clearer. Maybe I am not understanding it properly.
