Access point provides interworking function between core network presence services platform and incompatible mobile device

An access point 50, e.g. within a home or office 40, comprises a wireless interface, enabling connection with a mobile communications device 30 using a cellular wireless communications protocol, and an interface for connection to a core network 20 of a cellular wireless communications network. The core network 20 comprises a presence services platform, which provides presence-based services to compatible mobile communications devices, e.g. Instant Messaging (IM). The access point 50 is able to act as an interworking function, or "proxy", between a presence services platform of the core network 20 and an incompatible mobile communications device 30 camped on the access point 50. The presence of a user may be indicated to the presence services platform when the incompatible mobile communications device 30 roams onto the access point 50. Therefore, legacy GSM and UMTS mobile communications devices, for example, can take advantage of new service capabilities available through systems such as IMS, while they are camped onto the access point 50.