An NAI resolution mechanism for GPRS and TETRA PMR networks

Abstract

Dialup users of data networks that use the point-point protocol (PPP) make use of a network address identifier (NAI) for user identification. NAI is also being used for roaming and tunneling service in data networks. On the other hand, cellular networks make use of an alternative user identification format which is usually the international mobile subscriber identity (IMSI) or the mobile identification number (MIN). Similarly, terrestrial trunked radio (TETRA)-based professional mobile radio (PMR) networks make use of the individual TETRA subscriber identity (ITSI) for user identification. With the impending integration of cellular/PMR networks and data networks, it is desirable to have a one-one mapping between IMSI/MIN/ITSI and NAI. An operational procedure is needed whereby such a mapping occurs within the network and is transparent to the user. The Mobile IP working group within the IETF is currently investigating such a mapping for cellular networks. However, no mechanisms have been described for GPRS or TETRA networks. We outline a mechanism for such a mapping and the associated operational procedures when the cellular network is a general packet radio service (GPRS) network and also when the access network is a TETRA PMR network.