Sometimes to understand or to explain features, concept etc…you need to use the appropriate words. This is what I explored with Cisco Unity Connection – Cisco Voice Mail solution – which is not obvious to master all its components regarding the complexity of this product, especially when you start with it or when you are asked to explain it. This is why you need to always look at which words you should use. As an example Default System Transfer versus Default Transfer Restriction Tables.
On Cisco Unity Connection, there are Restriction Tables that prevent Toll Fraud using the transfer rules to transfer call to External numbers such mobile phone or international numbers.
Two Restriction Tables are sometimes confused: Default System Transfer and Default Transfer, so what is the difference?
1-Default System Transfer is applied when UNKNOWN extension calls Unity Connection and it is invited to transfer a call to PSTN for example through the opening greeting call handler.
2-Default Transfer is applied when KNOWN user or Extension tries to modify the phone number that is used for call transfer via TUI (Telephony User Interface) or PCA (Personal Communications Assistant).
Demystify and Simplify 