AT T Lowers Price on Internet Calling Service  WASHINGTON (Reuters) - AT T Corp &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=T.N qtype=sym infotype=info qcat=news"&gt;T.N&lt;/A&gt; on Thursday said it  was lowering the price on its CallVantage Internet calling  service by \$5 per month, matching the price from several other  suppliers.