By a 'coincidence' according to the company, T-Mobile will be upgrading network coverage inside the Moscone Center in San Francisco to test a 1900MHz HSPA+ "4G" network during the time that Apple's WWDC convention will be there, thus making it possible for unlocked iPhones and other smartphones to utilize the service. While T-Mobile does not officially carry the iPhone, it has been aggressive is seeking iPhone customers, and sells microSIMs and plans tailored to iPhone users.
