Up to 80 G.729 calls on dual Xeon. I think that is a voicemaster L3. Brand new Cisco 5350 is cheaper and will handle twice as much calls.
http://www.digium.com/index.php?menu=product_detail&category=extras&product=G729
“Internal testing with dual Intel® Xeon 1.8GHz processors allowed 60 concurrent calls. Dual Xeon 2.8GHz processors resulted in 80 concurrent calls.”