The MDA III supports GSM and Wi-Fi, and includes a retractable QWERTY keyboard that slips within the device when not in use. It will go on sale in Germany this September, where T-Mobile says it has already captured 40 percent of the PDA phone market with the MDA II.
"Thanks to integrated W-LAN technology, the MDA III allows very fast data exchange via wireless local networks, or at T-Mobile and T-Com HotSpot locations," said the company, adding that battery capacity has been increased by about 25 percent compared to the MDA II.
A spokesman for T-Mobile in the UK said that "nothing had been announced yet" regarding the launch of the MDA III in Britain.
Combining access to mobile phone networks and 802.11b is a key part of T-Mobile's strategy. In the UK it operates a string of Wi-Fi hot spots as well as its GSM network, and it is due to launch 3G services this summer.