Method and apparatus for integrating a soft mobile voip client in a cellular pc card

An apparatus is configured to communicate with a computer through a communications interface. The apparatus includes a soft mobile phone client and a cellular modem. The soft mobile client provides a Voice over Internet Protocol (VoIP) communication session, and includes a first set of a plurality of communications modules which does not include a non-access stratum (NAS) module. The cellular modem provides cellular Internet Protocol (IP) connectivity to the computer, and includes a second set of a plurality of modules having a NAS module. The soft mobile phone client establishes IP connectivity through the cellular modem and provides IP connectivity to the computer on a condition that a pre-existing IP connection via the computer is not available. The soft mobile phone client includes a software module encoded to implement a graphical user interface (GUI) function, which enables a VoIP communication session to be initiated by the user.