AT&T Inc is getting close to bringing its mobile phone call quality to where it should be, Chief Executive Randall Stephenson said in a CNBC television interview on Tuesday.

He was responding to a question about AT&T's network, which is under strain due to heavy Web surfing by users of the Apple Inc iPhone, particularly in densely populated markets such as New York City and San Francisco.

We've been going hard at the voice quality issue, Stephenson said.

AT&T, the exclusive U.S. operator for iPhone, said last month that it aimed to resolve network operating problems by the end of this summer.

Stephenson also repeated his plans for expanding U-Verse, the company's home video and broadband service, to a potential of 30 million consumer homes from roughly 23 million today.

(Reporting by Sinead Carew; editing by Leslie Gevirtz)

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