FACTBOX-Key developments for U.S. cell phone market

NEW YORK (Reuters) - Apple Inc.'s music- and video-playing iPhone is a far cry from the clunky 30-ounce device Martin Cooper made the first cell phone call from on April 3, 1973.

Here are some key developments in the U.S. cell phone market:

* 1947, Bell Laboratories engineers Douglas H. Ring and W. Rae Young propose the idea of mobile communication through signals sent from hexagonal cells located on the corner of cell towers

* 1968, Bell Labs and AT&T propose a cellular system to the Federal Communications Commission featuring small broadcast towers covering a radius of a few miles. Collectively, the towers would cover a larger area and would pass calls along as a caller traveled

* 1973, Motorola Inc.'s Martin Cooper makes the first mobile phone call. The phone was 10 inches tall, three inches deep and an inch-and-a-half wide

* 1978, public trials of a cellular system devised by Bell Labs and AT&T start in Chicago

* 1982, the FCC allows the use of commercial cellular service in the United States. At that time, commercial service had been established in Japan and several European countries

* 1987, the number of mobile phone users exceeds 1 million. The first handheld mobile phone by Ericsson makes its debut

* 1999, Canadian firm Research In Motion rolls out the Blackberry, a two-way e-mail pager

* 2001, basic Web sites specially designed for mobile phones start appearing on U.S. green screen phones

* 2002, U.S. wireless service providers start to add more capacity to their networks to speed up mobile Web surfing

* Late 2004, Motorola debuts the sleek Razr mobile phone to much fanfare at Cingular, now part of AT&T Inc.

* In 2007, some gadget enthusiasts wait in line for days for the iPhone, the first phone from Apple, better known for its iPod music players and Mac computers. The device, with service offered exclusively by AT&T, has a Web browser and a music and video player.

Sources: www.inventors.about.com, www.library.thinkquest.org, Technology Review and Telephony