We have recently had a Mitel VOIP system installed in our offices and we are trying to set up an out of office divert for IT support.
The phones we are using are 5312 IP phones running on a ICP3300 system. When we configure the phone for call forwarding always and enter the number, it will only divert internal calls. When you try to call the DDI number for the handset using a mobile, it says "Call Rejected" and using the IP phones it says "Call Barred".
I have looked through all the class of service and class of restriction information on the ICP3300 and can't see anything that could explain the problem.
Does anyone know if there is an issue with the Mitel VOIP system forwarding from trunk to trunk?