The Android-based G1, sold through T-Mobile, is close to selling 100,000 units in the UK six months after its debut, a feat that means it has “outstripped” sales of all other T-Mobile handsets, according to the operator. T-Mob also confirmed today, that it would be unveiling a second Android cellphone this summer, though declined to say which model phone it would be. Rival Vodafone (NYSE: VOD) has an exclusive agreement to sell the Magic, the second Android phone from HTC, the Taiwanese cellphone maker behind the G1.

The G1 will also get a software update in May. The “Cupcake” upgrade, or Android 1.5, will give users a touch-screen keyboard as well as the ability to record and play video among other features. Currently, T-Mobile UK offers the G1 for free on a £30 monthly contract that runs at least 12 months and includes unlimited web browsing. Last week, Deutsche Telecom, T-Mobile’s parent company, said it had sold one million G1s.