Let's look at some more N-1 Call Scenarios. The diagram on your left illustrates a scenario for Wireline Long Distance Calls.
Long Distance - LNP/LRN Capable IXC):
- Caller A calls long distance to Caller C from outside the porting area.
- LEC-3 routes the call to the caller's pre-subscribed carrier without any requirement to determine the LRN.
- The pre-subscribed IXC (IXC-1) is the N-1 carrier which determines the LRN by performing a Database Query (or "database dip"), and routes the call to LEC-2. If IXC-1 does not have a direct connection to LEC-2, calls may be terminated through tandem agreement with LEC-1, without change in the N-1 carrier responsibility.