As well as functioning as a mobile phone the Treo 180 includes a miniaturised keyboard, while the g180 uses Palm's Graffiti handwriting recognition.
The company believes that telephony will prove to be the killer application for PDAs because of the convenience of using one mobile device rather than two.
In a radical redesign, the new Treo is smaller and slimmer than existing models and has a lid with a window so features and functions can still be accessed. A "jog rocker" wheel is used to move a cursor to navigate the menu when the touchscreen is covered.
Both 180s can be used hands-free so PDA functions can be accessed during a phone call.