T-Mobile

A second big feature, or limitation, of the G1 – depending on your point of view – is that it is tightly tied to Google’s web-based email, contacts and calendar programs. In fact, you must have a Google ... account to use the phone, and can only synchronize the phone’s calendar and address book with Google online services. Unlike the iPhone, it doesn’t work with Microsoft Exchange, and it can’t physically be synced with a PC-based calendar or contacts program.