There’s a good article in Slate giving numbers on Fixed-Mobile Substitution in the US, and suggesting that a recent acceleration is due to the ailing economy:
…this year, the rate of decline of land lines has accelerated sharply. AT&T, which provides wired service in 22 states, just reported its second-quarter results. The wireless sector (72.9 million subscribers) continued to grow, adding 1.3 million net subscribers in the quarter. But revenues in the land-line voice services were down 7.8 percent from the first quarter of 2007. The number of retail consumer lines fell from 37.12 million in 2006 to 35.05 million in 2007, off 5.6 percent. In the first quarter of 2008, the company lost another 870,000 consumer land-line subscribers, or another 2.5 percent.
Verizon is suffering similar land-line declines. By the 2008 first quarter, its wireless unit had added 1.5 million customers since the 2007 first quarter. But the number of residential lines fell from 27.06 million to 24.11 million, a 10.9 percent decrease.
Qwest has seen its number of primary and additional consumer lines fall from 8.63 million in March 2006 to 7.17 million in March 2008, a decline of 17 percent.