Google would be happy to use AT&T's network If they could actually find it. Even AT&T armed with a flashlight and a map could not find portions of their network.
Google buys bandwidth from just about every Tier One backbone provider including AT&T see »www.fixedorbit.com/AS/15/AS15169.htm
What is AT&T boo-hooing about? Sprint and Level3 have better backbones anyway dump AT&T.