After years of mounting customer outrage over its clogged network, AT&T has finally scrapped its unlimited-data plan and raised the price on heavy data users. It’s a wonder it took so long. Since the iPhone debuted exclusively on AT&T in June 2007, Apple stock has risen 110 percent, while AT&T is down 38 percent. The $30-a-month unlimited plan was designed to attract customers, and with 50 million iPhones sold, it did. But AT&T’s network was crippled as a few users hogged bandwidth: 3 percent of AT&T’s smart-phone customers use 40 percent of its data. AT&T now offers a two-tiered system: 200 megabytes for $15 a month; two gigs for $25. Use more than that, and you’ll pay extra. Network strain is likely to ease as a result, and analysts believe others will follow AT&T and that the switch will usher in a new era of (more profitable) metered data-pricing.