AT&T Wireless has launched 3G mobile data service based on UMTS (also called Wideband CDMA) technology in Detroit, Phoenix, San Francisco and Seattle, confirming reports last week suggesting that it was about to unveil the service.

The company also will deploy UMTS in two more cities--Dallas and San Diego—before the end of this year. That plan potentially could make San Diego the first market in which 3G services from U.S. carriers will compete head to head—Verizon Wireless already offers CDMA 1X EV-DO service in San Diego. Both Verizon and Sprint are in the midst of launching EV-DO in other markets, but neither has confirmed specific cities set for these launches.

For now, AT&T Wireless’ launch of UMTS in four cities satisfies a contractual commitment it made to equity shareholder NTT DoCoMo when it invested in AT&T Wireless three years ago. That commitment was to commercialize UMTS before the end of this year.

“We were not going to miss this launch date,” John Zeglis, chairman and CEO of AT&T Wireless said during a conference call this morning. “It was very important to make it.” He called NTT DoCoMo the U.S. carrier’s “most valued” partner, and said the companies engaged in three years of “intense interchange and open discussion about how best to deploy [UMTS].”

Keiji Tachikawa, the former President and CEO of NTT DoCoMo, who now serves on that company's board of directors, attended AT&T Wireless’ launch announcement, and lauded the company’s efforts. He said DoCoMo now has about four million UMTS users in Japan, and has a goal of signing up 10 million by 2005.

All of the core network equipment for AT&T Wireless’ initial UMTS launches is being supplied by Nortel Networks. Other partners include Real Networks, which will run a 90 kb/s video service over the new network, Microsoft, Novatel and IBM, among others.

The new service will provide average wireless data speeds between 220 kb/s and 320 kb/s, with bursts up to 384kbps. Though not as fast as EV-DO, Rod Nelson, chief technical officer at AT&T Wireless, said UMTS gives the carrier “a path to the future that is more robust” than EV-DO. Nelson spoke of an eventual upgrade from UMTS to High Speed Downlink Packet Access (HSDPA), which supposedly can reach peak data rates of 14.4 Mb/s.

UMTS and HSDPA are also already in the plans of Cingular Wireless, which has a pending acquisition of AT&T Wireless on the table. Zeglis sais he is hoping to see that deal close within the next few months.