With a federal court scheduled to take up the AT&T-filed lawsuit against a Verizon commercial showing 3G coverage maps of the two carriers on Wednesday, Verizon Monday filed a rebuttal in a Georgia district court, in response to the AT&T claims.

In its confutation of the Microsoft claim that the coverage maps in the commercial are "false" and "misleading," Verizon said that the ad simply highlights a fact that most of the AT&T iPhone customers are already aware of.

In its 53-page defense document, Verizon said: "AT&T did not file this lawsuit because Verizon's 'There's A Map For That' advertisements are untrue; AT&T sued because Verizon's ads are true and the truth hurts."

About the comparative wireless coverage maps showing Verizon having five times more 3G coverage than AT&T, Tony Melone, Verizon's chief technical officer, said that network capacity is the key issue. Melone added that AT&T lacks enough 3G capacity required to handle the growing demand resulting from the release of the Apple iPhone, for which it is the exclusive carrier in the US.

Verizon argued that the ad merely points out the reality - that AT&T lacks 3G coverage in parts of the country's West, South and Midwest. Furthermore, even in areas that have AT&T's coverage, users need to default to slower '2G' or 'Edge' networks, in case the local 3G network is loaded.