Subscriber registration method

#The invention relates to registration of subscribers for roaming in a visited network.

#At present, it is not possible for a subscriber to register in a visited network if the visited network does not have a roaming agreement with the subscriber's home network, or if the home network forbids registration to a particular subscriber.

#One approach to addressing this problem, described in PCT Patent Specification No. WO99/46926 (Ericsson) involves use of an Intelligent Pre-paid Service Card. This allows the mobile phone itself to deduct the call cost and so a pre-paid phone can be used in a visited network while roaming. While this approach appears to be useful for roaming pre-paid users, it does not address the situation where the user does not have this functionality in her phone or in general is not a pre-paid user.

#The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:—

#FIG. 1 is a flow diagram illustrating a registration method of the invention;

#FIG. 2 is a diagram illustrating signalling for a situation for which there is no roaming agreement; and

#Referring to FIG. 1, the invention provides a registration method comprising the following steps, at a high level.

#1. A subscriber of a home network roams in a visited network which does not have a roaming agreement with the home network. The subscriber turns on her handset, which attempts to register with an MSC/VLR.

#2. As there is no roaming agreement, the registration message (e.g. REGNOT in ANSI 41, or Location-Update in GSM) from the MSC/VLR is routed to an auxiliary HLR in the visited network. The auxiliary HLR function is provided as a conventional existing HLR.