A customer has a Mitel 470, v6.1. The room phones are Teledex phones with programmable buttons. One of the buttons is programmed for wake-up calls. The customer is reporting that the wake-up call button is ringing busy. I thought perhaps the buttons may be programmed wrong, so I asked him to dial the wake-up code, *9601. He reports that dialing the code also produces a busy signal. I have not been on site yet, but I VPN'd into the system and I don't see anything wrong but I may be missing something. What would cause *9601 to not be functional?