I'm in the LD world, and from the IXC perspective, when dealing with our customers (either LECs or retail/wholesale), the idea is TELCO indicates the actual owner of the facility going to the customer premise, and CARRIER is the group who either ordered the circuit or where it eventually terminates. In some cases, like in MCI, who have local presence and long distance presence, it could be the same company (but different organizations). In most cases, TELCO are the folks who wire up to the demarc block and CARRIER are the ones who provide the service over the circuit.