IS-41


IS-41, also known as ANSI-41, is a mobile, cellular telecommunications system standard to support mobility management by enabling the networking of switches. ANSI-41 is the standard now approved for use as the network-side companion to the wireless-side AMPS, IS-136, cdmaOne, and CDMA2000 networks. It competes with GSM MAP, but the two will eventually merge to support worldwide roaming.
IS-41 facilitates inter-switch operations like handoff and roaming authentication. IS-41 evolved through revisions 0, A, B, C, D, and E with increasingly robust and distributed call processing between switches and their roamer databases. To describe IS-41 messaging requires special terminology to designate the telephone call's originating and terminating switch, called an MSC and databases called VLR and HLR. For handoffs the messaging is between switches. For roaming and authentication, the messaging would include an HLR and a VLR. In both cases, the PSTN may be needed to carry messaging.