A voice over IP (VoIP) softphone access module (VSAM) comprises a softphone client installed on a portable memory device (PMD). The softphone client is installed in its own read-only partition. The softphone client is adapted to autorun from the PMD when the PMD is connected to a computing device and to load an instance of the softphone client in the volatile memory of the computing device. When used with a computing device comprising a duplex audio system with analog-to-digital conversion and an Internet connection, the VSAM permits a VoIP service subscriber to send and receive VoIP telephone calls through a VoIP service provider gateway. The VSAM may be associated with an activation code that when sent to the VoIP service provider gateway associates a user with pre-paid softphone usage credits. Alternatively, the softphone client is installed on CD.