TABLE OF CONTENTS It is my ambition to say in ten sentences what everyone else says in a book what everyone else does not say in a book.
Friedrich Nietzsche, Twilight of the Idols
The earliest version of ANSI-41 was written to define a way for first-generation Advanced Mobile Phone System (AMPS) networks in the United States to communicate with each other in order to facilitate roaming. Roaming among AMPS networks before IS-41 was a nightmare of phone calls to help desks, arrangements with credit cards, and missed calls even after all the preparations before travel. The specification was eventually expanded and altered to include TDMA (IS-136) networks and then altered again to include functionalities for CDMA (IS-95) networks. In all of its versions, it specified mobility management and call establishment, which had to be enhanced in subsequent versions of ANSI-41. Until recently, it was seen as a specification limited to the E interface. It is, in fact, the equivalent of the MAP protocol for CDMA and TDMA networks. As the MAP protocol, it is an application part using TCAP for transaction capabilities and SCCP over the ANSI SS7 MTP protocol.
The functional entities involved in the IS-41 protocol are the same as for GSM networks, MSCs, VLRs, HLRs, and so on, although some of the functional architecture is quite different from that of GSMs, as discussed in the following sections.
In IS-41, when a cell phone receives or initiates...
