By Sam Oliver

Published: 09:05 AM EST

AT&T, the exclusive provider of the iPhone in the U.S., announced this week that it has strengthened its 3G signal in the populous Tri-State Region, and that further nationwide network improvements are also planned.

The wireless carrier said that it has deployed spectrum in the 850MHz across "large portions" of New York City, Long Island and New Jersey, and customers in that area will have better reception and speed, as well as better coverage indoors. The company noted that the 850MHz spectrum used is considered "high quality," and has been enabled for 3G use at more than 1,600 cell sites in the New York metropolitan area.

"AT&T's ongoing investment to build broadband networks helps to create jobs, fuel economic growth and enable our customers to quickly access the content that matters most to them," said Jay Summerson, vice president New York, AT&T external affairs. "Our customers have embraced smartphones and upgrades like the additional 3G spectrum deployment allow them to enjoy the benefits of these devices and mobile broadband for years to come."

The nation's second-largest wireless carrier has plans to further improve its 3G coverage nationwide in the fourth quarter of 2009 with HSPA 7.2 technology, which will give customers faster mobile broadband speeds. The company expects that upgraded to be completed in 2011.

In addition, nearly 1,900 new cell towers are planned to be built across the U.S. this year. Customers in the Tri-State Region should also expect to see further improvements, as the company will continue to add cell sites in that area.

This year, the addition of unlimited Wi-Fi access at AT&T hotspots for iPhone users led to a large increase in Wi-Fi connections. In the first half of the year, AT&T handled 25.6 million Wi-Fi connections -- more than in all of 2008.

While the breakthrough success of the iPhone since its launch in 2007 has brought millions of customers to the AT&T network, the additional bandwidth used by the data-heavy device has had a significant impact on network performance. Some surveys have indicated that while users are happy with their purchase of the iPhone, the AT&T network is the least-loved aspect of Apple's device. Both Apple and AT&T have been sued for over-saturating its 3G network with iPhones.

In its response to an inquiry from the Federal Communications Commission last month, Apple gave a glimpse into its contract with AT&T and revealed the company's internal concerns about App Store software that might over-tax its wireless network.

"From time to time, AT&T has expressed concerns regarding network efficiency and potential network congestion associated with certain applications, and Apple takes such concerns into consideration," Apple said in its letter.

Many have speculated that bandwidth capabilities are the reason AT&T has not yet allowed tethering or MMS capabilities on the iPhone, even though other worldwide carriers already offer those capabilities. The U.S. wireless carrier has said that the features would arrive for iPhone users late this summer.