Maybe it's legal, but moral is another question. States like Florida treat workers as disposable, and others consider them a great resource. I worked for one firm that used the phone speakers to record, not only sales calls, but general office chit chat. As to personal calls, why are you making them on company time? In this economy, you can't afford to slip up, or fifty of us will be lining up for your job.
Kinda makes me wonder if they are considering an automated phone system, and are being marketed to by VOIP providers promising huge savings. (VOIP = Voice over Internet Protocol)
They could also be working stats to find out what customers respond well to, so they can reduce your interactions to scripts designed to "delight" customers, in the shortest response time.