Potential customers may have a difficult time getting their hands on the upcoming Android-powered G1, as T-Mobile said it has sold out of its presale inventory.

"Given the great anticipation and the heavy presale demand for the T-Mobile G1 with Google, we nearly tripled the number of phones initially available for delivery on our Oct. 22 launch date, and have sold through them all," T-Mobile said in a statement.

The Android platform was introduced by Google last November with the goal of bringing the openness of the Web to a mobile industry that's traditionally more closed down. The open source Android operating system is expected to be on a plethora of different handsets, and it's also seen as a way for Google to migrate its lucrative ad platform to the mobile space.

The G1 was introduced by Google, HTC, and T-Mobile in late September, and it will be the first mobile phone with the Android OS. The touch-screen device will feature a QWERTY keyboard, built-in Wi-Fi and GPS, 3G network connectivity, and Bluetooth.

T-Mobile did not specify how many G1 handsets it made available for preorder, or how many would be available on launch day, but it did say customers could continue to make preorders and receive the handset after the launch date. A recent report by Strategy Analytics suggested that T-Mobile could sell up to 400,000 units by the end of the year.

One possible hurdle to hitting this sales figure is T-Mobile's relatively small 3G footprint. The G1 greatly benefits from having mobile broadband access, but the fourth-largest U.S. carrier only has 3G service in 13 markets. But T-Mobile is working to expand this network, and it expects to have 3G connectivity in 27 major markets by the end of the year.