with the setup you have, no way of telling how many calls are missed.. How about this. 1. Have Hunt group 450 ring over after 30-40 seconds to another hunt group, say 451. 2. Hunt Group 451 would have the same setup as HG 450.. 3 On call reports, just look for the calls that went to HG 451 and those would be the ones that were missed... You can play with the timeout on the first hunt group.
Not 100% accurate.. but pretty close !