How to Configuring Feature Access Codes in Call Manager Express ?

Feature Access Codes (FACs) are special patterns of characters that are dialed from a telephone keypad to invoke particular features. For example, a phone user might press **1, then press 2345 to forward all incoming calls to extension 2345. Typically, FACs are invoked using a short sequences of digits that are dialed using the keypad on an analog phone, while IP phones users select soft keys to invoke the same features. In Cisco Unified CME 4.0 and later, the same FACs that are available for analog phones can be enabled on IP phones. This allows phone users to select a particular feature or activate/deactivate a function in the same manner regardless of phone type. FACs are disabled on IP phones until they are explicitly enabled. You can enable all standard FACs for all SCCP phones registered in Cisco Unified CME or you can define a custom FAC or alias to enable one or more individual FACs. All FACs except the call-park FAC are valid only immediately after a phone is taken off hook. The call-park FAC is considered a transfer to a call-park slot and therefore is only valid after the Trnsfer soft key (IP phones) or hookflash (analog phones) is used to initiate a transfer.