 In 1981 McCaw came across an AT&T document about the future of cellular telephony, which predicted that by the turn of the century there would be 900,000 cellular subscribers in the United States.Intrigued, McCaw found that the licenses for cellular spectrum were being sold at $4.50 per "pop", meaning he could build a base for future subscribers for very low cost.By 1983, McCaw Communications had purchased licenses in six of the 30 largest US markets.