AT&T HAS BEGUN the transition of Verizon Wireless customers in the 79 markets that they aquired last year.  Customers are being alerted that they will soon be joining the AT&T family.  A welcome letter detailing the initial phase of the transition is being sent out to the soon-to-be former Verizon Wireless subscribers.  The letter confirms that AT&T is activating its service on a market-by-market basis and is working on integrating the two networks.  AT&T will then being the transition of customers over to its service, plans, and handsets.