Jerry Thibeau suggested to us, years ago, to pay our BDC by the phone call. We introduced a "Calls per Hour" metric and it was the most successful time the BDC ever had. The metric was a pain in the butt to track and I've been told that's why it was dropped from the pay plan. But damn, I sure loved the productivity it yielded!
We found that 8 calls per hour was the average and that our appointment setting problem wasn't due to talent; it was due to volume of phone call follow up. When you pay someone on the number of calls you eliminate the universal "lazy-fier" called email. People are much easier to get an appointment out of over the phone.