AT&T is launching its 4G Long Term Evolution (LTE) network across various cities in the U.S., marking its first foray into the new high-speed data standard.

The nation's second largest wireless network provider said on Sunday that it rolled out its new data network in San Antonio, Chicago, Dallas, Houston and Atlanta.

It marks the first time the provider has offered the service, which promises much faster mobile data-download speeds  than its current 3G -- or third generation network. But its not the first company to offer LTE.

The move puts AT&T closer to its largest rival, Verizon Wireless, which has already rolled out 4G access to 25 cities.  The smaller MetroPCS also has 4G.

AT&T CTO John Donovan took veiled shots at Verizon in his official blog.

Our largest competitor's wireless network is 60 percent slower on average nationally, he said. The closest competitor is 20 percent slower.

Donovan explained that its current HSPA+ network, which is an enhanced 3G network, does speeds that other company's 4G networks do.

This means customers will get a smoother experience as they continue to roll out LTE.

That matters, because when we begin commercial deployment of LTE in mid 2011, customers on our LTE network will be able to fall back to HSPA+, he said.

As they do, they'll receive a more consistent mobile broadband experience that supports simultaneous voice and data connections and higher speeds than the others can provide outside their LTE footprint.

But one problem is company still needs to catch up with rivals with 4G hardware as well.

There are only three AT&T devises that currently work with LTE: the USBConnect Momentum 4G modem, Elevate 4G mobile hotspot and HTC Jetstream Android Honeycomb tablet.

AT&T's upcoming HTC Holiday, will reportedly have a 1.2 GHz dual-core Snapdragon SoC processor, a 540×960 display, run Android 2.3.4 and  feature HTC's Sense 3.0 user interface, according to AT&T.

The company said it will bring LTE service to 15 other markets, potentially covering 70 million users, by the end of the year.