Mobile phone operator T-Mobile is offering one of the world's first mobile phone-based navigation systems using three different wireless technologies.

T-Mobile's NaviGate BlueKit makes use of GPRS (general packet radio service) mobile data, cordless Bluetooth and GPS (global position system) satellite technology, allowing customers to transform their mobile phones into in-car navigation systems.

The technology works like this: in the vehicle is a GPRS-enabled phone equipped with the NaviGate software which users can install themselves. The phone connects to a small GPS receiver mounted in the vehicle via Bluetooth cordless technology.

When users enter a destination, that information is transmitted over the GPRS network to T-Mobile's traffic server which calculates a route and sends the data back to the mobile phone. As users travel, they are tracked by the GPS, which sends signals to the phone activating voice messages and phone displays with route instructions, similar to navigation systems that store route data in CDs and are installed in cars today.

T-Mobile subscribers can also choose to have near real-time traffic updates, with route alternatives sent directly to their mobile phones, according to company spokesman Husam Azrak. "This service, however, requires that users retain a GPRS connection after beginning their trip so that their handsets can be frequently updated with current traffic information," he said.

The German operator designed the new mobile phone navigation system based on technology it developed earlier for a line of wireless PDA (personal digital assistant) products. The major difference between the mobile phone and PDA products is the former's Bluetooth capability, according to Azrak.

Initially, NaviGate BlueKit software will be available for Nokia's 3650 and 7650 models only but other phone models will follow, T-Mobile said.

The cost of mapping a single route is ?1.99 (about £1.35). Applicable GPRS call fees are charged on top of that. To promote the new service, T-Mobile is offering the NaviGate BlueKit with a Nokia 3650 for ?349,95 (£240).

The cost of the NaviGate BlueKit without a handset is ?249.95 (£170). In addition to software, the kit includes a wireless GPS receiver with battery and integrated electronic charging equipment, as well as a charger for the GPS receiver for the motor vehicle. The GPS receiver works for up to 10 hours on a fully charged battery.