by Laura Rich, contributor

The world will have to wait for sharper barbs between Apple and AT&T (ATT) over who’s to blame for dropped calls on the iPhone. In an appearance at the Fortune Brainstorm Tech conference in Aspen on Friday, AT&T mobility and consumer markets president and CEO Ralph de la Vega was succinctly complimentary about its relationship with the phone maker that Wired magazine has described as a “loveless celebrity marriage.”

“I think it’s been a net positive,” he said.

Speaking at the All Things D conference last month, Apple (APPL) CEO Steve Jobs seemed lukewarm about it.

“They are doing pretty well, actually, in some ways, and they have some work to do in other ways,” he said. “They have the fastest 3G network, and it’s improving. I wish I could say ‘rapidly,’ but I think it’s moderate-rate improvement.”

On Friday, de la Vega talked about the efforts to improve infrastructure, including the recent doubling of capacity in New York, where the complaints have perhaps been the loudest. Spectrum and technology to distribute it more efficiently were added to every cell tower in the city, the company said last month.

Elsewhere, AT&T is working to get more spectrum allocated to its network by the Federal Communications Commission, and is pressing ahead on building out its fiber network.

“It’s a process that just takes time,” de la Vega said. “We have a very deliberate process to get fiber, but it’s a couple of years’ journey.”

In the meantime, AT&T may aim to strengthen relationships with its other mobile partners, including Hewlett-Packard (HPQ), which recently acquired smartphone maker Palm for $1.2 billion.

“I think they have the opportunity to make the premier OS,” said de la Vega.

In a poll, audience members at the event voted for Android to lead the mobile OS pack over the next few years.

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