I have an Hotel with a Mitel SX200, just install IP Office/Partner in the sale dept. Using a Butt set on one of the unused analog port of the SX200 was able to call front desk and they were able to call me. Hook this port into unused CO port of the IP Office, can pick up the line and get intercom dial tone from the Mitel and call any ext. But if the front desk call up to the IP Office all I get is a steady red light on the co port and can not pick up. It works with a butt set and not the CO port of the IP office. HELP

The CO is probably a member of the main incoming line group so it will ring based on the group assignments. Check your button as well to see if the line is set to ring on that phone.