Handspring's Treo combines a GSM phone and a PDA running the Palm operating system. As well as making and receiving phone calls, the Treo can also access the Internet over a GSM network.
The Treo - and a GSM version of Research In Motion's Blackberry wireless e-mail device announced by mmO2 last year - will be joined in May by the XDA, an mmO2-branded PDA running Microsoft's Pocket PC software.
The network operator plans to use the XDA as a way to promote new services based on other Microsoft software packages.
The services will include mobile access to data held on Microsoft Exchange servers, and secure access to corporate intranets over virtual private networks (VPNs), and over GPRS and GSM networks.
The companies also plan to extend the services over future 3G mobile networks.
Initially, Microsoft and mmO2 plan to let enterprises develop their own services based on Microsoft's Mobile Information Server, selling the necessary software through their existing systems integrator and reseller channels.
ASPs could offer managed services in the future, mm02 said. However, the primary route to market for the services will be the XDA, manufactured by High Tech Computers, the company behind Compaq 's iPaq PDA.
The XDA, when it arrives in Europe later this year, will be available bundled with back-end software and will sell for around £400 for users signing a contract with mmO2, according to a company spokesman.
Access to the new enterprise services over GPRS will not be restricted to users of the XDA. Handspring and mmO2 plan to issue a software patch for the Treo enabling GPRS operation in the third quarter of this year.
The Treo will go on sale in the UK at the end of March for about £350, which includes an airtime subscription.