Calls spanning sub-domains with independent call linkage

[0015] Turning now to the drawings and more particularly, FIG. 1 shows an example of a preferred embodiment communications network or Public Land Mobile Network (PLMN) 100, wherein calls tunnel between endpoints regardless of infrastructure protocol. In particular, calls may tunnel between base station controllers (BSCs) 102, 104, each of which includes one or more cells serviced by a local base transceiver station (BTS) 106, 108. Each BSC 102, 104 may be a different switching sub-domain (e.g., a different service area) within the network 100. Mobile Subscriber (MS) units or wireless communications devices 110, 112, 114, 116 in the cells wirelessly communicate through the particular local base station 106, 108. Each MS 110, 112114, 116 may be any appropriate wireless communications device such as a second generation (2G) or third generation (3G) wireless communications device, e.g., a typical cellular phone. Further, each switching sub-domain is connected to a number of communications