Engineers from Google and HTC have spent three years developing Android software and smartphones before T-Mobile's unveiling of the G1.
Executives from both companies started talking about a collaboration as long as five years ago, but those discussions didn't turn into anything substantial until later, said John Wang, chief marketing officer of HTC.
"Google makes software. They needed a hardware partner," he said. HTC engineers remain at work in Google offices today.
The companies showed off the results of their work on Tuesday in New York City, with top executives from Google, HTC and T-Mobile present.
The G1 handset, with a touchscreen dominating most of its face, will first be available in the US on October 22 for $179 with a two-year voice and data service contract. T-Mobile said the smartphone will hit the UK by Christmas.
The key to the new handset is the Android software, an open source OS and loads of applications that are already available. The mobile phones and software are designed to work with a lot of current Google services, including Google Maps and Google Maps Street View, as well as YouTube.
HTC believes working with Google on the Android project gives it a big advantage over other mobile phone makers.
Handset builders Motorola, Samsung and LG are all currently listed as members of the Open Handset Alliance, the group of corporate supporters Google formed around Android. The companies are believed to be at work designing Android-based handsets but none of them have announced anything yet.
HTC plans to make more of the handsets.
"This will not be out last Android phone," said Wang. "This is just the beginning."
He declined to comment specifically on whether new Android-based handsets were already in the works from HTC.