A cellular data gateway situated at a mobile telecommunications switching office (MSC) is provided for interconnecting an originating mobile modem of an analog cellular system to an answer modem of a public switched telephone network (PSTN) when one of the either the cellular side or the PSTN...http://www.google.co.uk/patents/US5787363?utm_source=gb-gplus-sharePatent US5787363 - System and method for connect message synchronization of modems in a cellular data gateway 
