Patent ID: 7751549

Claim:
A tandem switch migration method to migrate at least some end users from an old tandem switch of a Public Switched Telephone Network (PSTN) to a new tandem switch using a Local Number Portability (LNP) capability, the method comprising: configuring a Local Routing Number (LRN) information of the PSTN in order to direct inbound calls from the PSTN over a first Time Division Multiplex (TDM) trunk line through the new tandem switch and to an old local service node, wherein SS7 signaling is exchanged between the PSTN and the new tandem switch; programming routing information of the new tandem switch to direct inbound calls for only a portion of the end users from the PSTN to a new local service node after the portion of the end users of the old local service node have been physically moved from the old local service node to the new local service node; and configuring the old local service node to route outbound calls through the old tandem switch to the PSTN for remaining end users that have not been physically moved from the old local service node to the new local service node.