Should I be able to use *66 (Busy Auto Redial)? (Or, how do I make it work?)
I have PhonePower VOIP, and they have *66, which is what you do when you get a busy signal and you want to know when the other end's line is free (so you can call them - "them" being whomever you're trying to call).
*66: When activated, the last phone number that the user dialed is automatically redialed until the called party is connected or 30 minutes passes.