This is a bit ironic. T-Mobile USA has turned to AOL (NYSE: AOL) to help sell the Google (NSDQ: GOOG) phone. AdAge.com reports that the carrier is buying 1 billion ad impressions across AOL’s Platform-A ad network next week on Monday and Tuesday that will help promote the phone that is the T-Mobile G1. The purchase marks Platform-A’s single biggest online ad buy. The network serves up to 3 billion ad impressions a day and reaches 90 percent of Internet users. The ads will run on AOL sites such as AOL Music, AOL TV, Engadget and TMZ, as well as many of the sites on ComScore’s top 100. The report said the campaign will reach 81 million people, and that it will cost about $1.5 million for the 1 billion ad impressions, putting the CPM at $1.50. All Things D reported that number sounds high, and that their sources say the CPM will be closer to the $1 to $1.10 range.