A smart card is used with a network based system to providing portable telecommunication and computing services. In an exemplary embodiment the smart card holds a user authentication code and user telephony account information. The smart card transfers the user authentication code and the account information to one of a plurality of geographically dispersed card readers which are each connected to a local telephony device. When the smart card is plugged into a first card reader, telephone calls directed to the smart card user's follow-me telephone number are received at a first local telephony device. When the smart card is plugged into a second smart card reader, telephone calls directed to the follow-me telephone number are received at a second telephony local device. Hence the user is enabled to receive and place calls using any of the geographically dispersed telephony devices as though they were his/her own personal landline or cellular telephone supplied by his/her telephony services provider.