Hi,
similar setup here: two boxes (in different countries), each with a couple of BRI Interfaces, connected via SIP Trunk
To be able to dial extensions on server2 from server1, I added an outbound route for the sip trunk with a dial rule that specifies all the extensions on server2. Route is marked as intra-company so I don’t loose the CID Information. context for the trunk is specified as “from-internal” to get acces to all extensions defined at the server2
To make these extensions on server2 reachable wia DID form pstn I added something to extensions_custom.conf:
[ext-did-custom]
include => outrt-002-asterisk_berlin
You’ll have to check you extensions_additional to find the name generated for this route on your system; also be careful when reordering routes - name can change!.