Call Hunting CLASH with Voicemail

Voicepulse has told me that the reason why Call Hunting has refused to kick in for me when I have had Voicemail activated is a timing problem. They have told me that a 20 second ring count before hunting and a 30 second ring count before voicemail is too small an increment, that I need to give call hunting a much longer head start. They are recommending that I set the voicemail delay to 60 seconds so that call hunting will have a chance to begin instead of being aborted by voicemail.

Has anyone else had this song-and-dance with them? What experience do you have with hunting and voicemail with them or others?

They also tell me that they are satisfied that they are delivering false busy signals after hunted phones are not picked up. Is this False Busy Signal phenomenon commonplace with other providers? Why in the world would they think it is a reasonable thing to do?