AT amp;T CallVantage Service To Be Available in More Than 600 Best Buy &lt;b&gt;...&lt;/b&gt; BEDMINSTER, NJ, Aug. 23 /PRNewswire/ -- AT amp;T today announced that Best Buy will be among the first national retailers to offer AT amp;T #39;s residential Voice over Internet Protocol (VoIP) phone service, AT amp;T CallVantage 