Aastra SIP 53I Administrator's Manual page 293

Configuring Operational Features
Operational Features
You can enable/disable "Directed Call Pickup" using the configuration files or the
Aastra Web UI.
41-001160-00, Release 2.1, Rev 04
Notes:
1. The default method for the phone to use is Directed Call Pickup over
BLF if the server provides applicable information. If the Directed Call
Pickup over BLF information is missing in the messages to the server, the
Directed Call Pickup by Prefix method is used if a value for the prefix
code exists in the configuration.
2. You can define only one prefix at a time for the entire BLF/List.
3. The phone that picks up displays the prefix code + the extension
number (for example, *981234 where prefix key = *98, extension =
1234).
Note: The "Directed Call Pickup" feature is disabled by default.
5-83