Client/server platform consisting of hardware and software for linking wireless applications with enterprise networks and the Internet; Computer software for use by communications service providers to access, create, collect, sort, remove, transfer, disseminate, organize or otherwise utilize voice, text, graphics or multimedia content over a global computer network and other networks; computer software for use in facilitating communications over computer networks, namely, electronic messaging software; server software for interfacing hand-held devices, such as pagers, cellular phones, and wireless PDAs, to host computers, servers and the global computer network; server software that allows access to centralized message stores and other data services via telephony interfaces; Computer software for synchronizing contact, calendar, task list and other information between a personal computer and a hand-held device; computer software for determining location, presence or availability of a hand-held device; Computer software for enabling mobile carriers to perform network maintenance and optimization tasks such as testing roaming links and optimized network routing; Computer software that enables mobile carriers to lower their subscriber acquisition costs