US Patent 6937862 Maintaining association in a communications network

A method for maintaining association between switching units in a network includes the steps of determining that a call is to be routed via a base station, routing units, and a switching unit. The call is then routed via the base station, at least one routing unit, a routing link, and a switching unit. An association message is transmitted to the switching unit to inform it of an address of an additional switching unit. A mobile station within a coverage area of the base station is capable of communicating with the switching units, and elements of the system are configured to address the additional switching unit to determine whether the mobile station is communicating via an appropriate path.