DISA stands for Direct Inward System Access and is a way to let inbound callers to reach any internal extension. Once answered the system will play a message inviting the caller to enter the extension number to be connected to. The system allows also to dial outbound numbers, usually protected by a PIN code.
Welcome message: is played to the calling party, usually asking to enter the extension to dial.
PIN: is requested to access this feature. It is required to set a PIN when outbound calls are allowed.
Allow outbound calls:
Block External Caller ID: Blocks the outbound Caller ID
Use CID Number: Override the caller ID Number and use this one. If left empty, use the caller caller ID Number
Use CID Name: Override the Caller ID Name and use this one.