T-Mobile plans to sell 400,000 to 500,000 Android Google (NSDQ: GOOG) phones in the fourth quarter, and will order up to 2 million devices from handset-maker HTC in the near future, reports a Taiwanese news site CENS. Quoting industry insiders, the site says at those volumes, it could lead to a $7 billion jump in revenue for HTC in Q4, and up to $18 billion in revenues next year. The T-Mobile G1, which is expected to launch Oct. 22 for $179 in the U.S., is being positioned against the iPhone. But as Silicon Alley Insider points out, selling up to 500,000 phones in 71 days would be about half the rate at which Apple (NSDQ: AAPL) sold its first 2G iPhone last summer, although still a big accomplishment. It’s worth pointing out that Google won’t make a dime from these sales, and instead will rely on advertising to make money. In that case, mass adoption is key.