A recent article in Business Week discusses the impact of VoIP on the RBOCs. The article highlights IBM's recent announcement to move to a VoIP network:

When IBM talks, Corporate America listens. So Big Blue created quite a stir on Nov. 7 when a top exec told a tech conference in Atlanta that it hopes to move 80% of its 300,000 employees to voice-over-IP phone systems by 2008. ... When the largest tech company on the planet announces it no longer needs the phone company to manage its calls, you can bet the communications landscape has fundamentally changed.

From BW Online | Why the Bells Should Be Very Scared
Referenced Thu Nov 13 2003 13:46:52 GMT-0700

I've been experimenting quite a bit with VoIP. I've got 200 VoIP phones going in a project that I'm working on and I'm learning a lot about the technologies and the vendors. The bottom line is that the technology is easier than many believe. Once IT departments figure out how flexible and simple this stuff is, there will be no holding them back.