Circuit bearer control

摘要

The invention makes use of the Short Message Service (SMS) or Unstructured Supplementary Services Data (USSD) capabilities present in today's cellular networks as a means of providing call control and presence signalling and, in particular, for providing the means of effecting hand-off at least from/to the cellular domain to/from the WiFi domain. SMS and USSD were originally designed as engineering channels, but SMS has become highly popular as a service in its own right. SMS and USSD are built into all existing cellular (GSM, CDMA etc.) network and predate the current GPRS overlay. In particular, SMS and USSD can be used while a call may be active in the cellular domain, and a handset may send and receive such messages, with an additional facility which may be used by the invention of receiving acknowledgements of successful receipt of an outgoing SMS by the messaged party—effectively a confirmation from the network. The present invention proposes to use SMS or USSD as a means of an adjunct call control and presence signalling in the cellular domain between a handset and the SIP domain.

主权项

1. In a radio access network system comprising a cellular domain and at least one WiFi domain, a method of call control comprising:
using a Session Initiation Protocol (SIP) Applications Server to control a call, irrespective of whether the call is originated in the cellular domain or in the WiFi domain; and using a radio access network channel of the cellular network to communicate call control signalling data to or from the SIP Applications Server when the call is originated in the cellular domain and when handover occurs (1) between the cellular domain and the WiFi domain and (2) between the WiFi domain and the cellular domain.