Trunk name for Inbound routing

Dear all,

I have a north american DID provider which allows me to receive call on its registered number and route onto a voip client of my choice, as long as I register it using user-id, pwd and their provided sip register.

Similarly, I have just received a FritzBox 7412 from 1und1 which works as sip server and allows me to register a softphone to receive and place calls using their service.

In both cases I register both accounts as trunks and I am normally able to receive calls either from the north american DID number or calls directed to my German number received with the 1und1 subscription.

Unfortunately I am unable to trap those calls in the inbound routing process as I am unable to identify the name of the trunk.

I tried either with the name that I associate to the trunk when I create it or the name of the user-id used to register to those servers.

Just to give an idea, every time I receive a call on my 1und1 number I get a log similar to:

Mar 3 20:33:53 VERBOSE[62491] chan_sip.c: Hangup call SIP/620-XXXX, SIP callid C9525D99E2B6E792@aa.bbb.ccc.ddd

Where XXXX changes at every call and aaa.bbb.ccc.ddd is the public IP of my 1und1 router which I conveniently hidden for privacy.

I cannot configure the north american DID service to automatically route all the calls to my SIP URI address, nor I can configure the FritzBox 7412 to route all the calls to my SIP URI address.

How can I trap all the calls coming through those trunks so that I can use the incoming route mechanism?

Thank you in advance for any help