Base station subsystem multiplexer with support for local switching
In one embodiment, a wireless system comprises a host MSC/VLR of a public land mobile network (PLMN) and a plurality of base station subsystems (BSSs). Each BSS includes a respective base station controller (BSC) and one or more base transceiver stations (BTSs). The wireless system further comprises a virtual base station controller (VBSC) communicatively coupled to the plurality of BSSs and the host MSC/VLR. The VBSC appears, from the perspective of the host MSCNLR, to be a base station controller for the BTSs in the plurality of BSSs. The VBSC and at least some of the BSSs include functionality for locally switching calls in the BSSs.
1. A method of determining, by a virtual base station controller (VBSC) in communication with a plurality of base station subsystems (BSSs), if legs of a call between a first mobile station and a second mobile station should be locally switched in a corresponding BSS, each call comprising a first leg associated with the first mobile station and a second leg associated with the second mobile station, the method comprising:
sending user-to-user information by a user-to-user signaling (UUS) service from the first mobile station to the second mobile station;
inserting, by the VBSC, the user-to-user information into at least one message that relates to the first leg of a first call, the inserted user-to-user information including at least one identifier;
receiving, at the VBSC, a plurality of messages related to setting up second legs of a set of calls;
checking the received messages related to the setting up the second legs of the set of calls to identify a selected message that includes user-to-user information comprising the at least one identifier; and
checking if the first leg and a second leg setup by the selected message are terminated in a same routing zone of a base station subsystem and, if they are, causing the first leg and the second leg setup by the selected message to be locally switched within the routing zone of the corresponding BSS.
2. The method of claim 1 , further comprising checking if the first leg of the first call is terminated in a routing zone that supports local switching, wherein the user-to-user information is inserted into the at least one message that relates to the first leg of the first call if the routing zone support locally switching.
3. The method of claim 1 , wherein the identifier comprises at least one of an identifier associated with a subscriber, and an identifier associated with a routing zone.