A "Camel-Back" Digital Organizer (CDO) system is described that is designed to attach to a cellular phone in the same manner as an auxiliary battery, and to interface with the phone through contact points available in the phone's interface port. The CDO system is preferably implemented as an add-on component...http://www.google.com.au/patents/US6505055?utm_source=gb-gplus-sharePatent US6505055 - Camel-back digital organizer and communication protocol for a cellular phone device
