Setting outbound Caller ID per DID to get national rates

National rates — the cheapest outbound tier — depend on the Caller ID your trunk presents, not on where your PBX or staff are located. A UK Caller ID on a call to a UK number keeps the call domestic and cheap.

1. Add a DID for the country you call most (from £3.38/month for a local or 03 number).
2. Set that DID as the outbound Caller ID on your PBX trunk, or per outbound route if you call several countries and want to switch Caller ID accordingly.
3. Make sure the trunk is not configured to withhold/anonymise Caller ID — hiding it drops you to standard international rates.

The US and Canada get national rates with no local Caller ID required. Verify the presented number with test line 1-555-555-0911 after any change.