To enable IP phone users to quickly transfer calls to an extension selected by a speed-dial or monitor line button without having to press the Transfer button use the command service dss under the telephony-service configuration mode.
This command is integrated into Cisco IOS Release 12.4(11)T or in Cisco Unified Callmanager Express 4.0(3). Same feature can be implemented in Cisco Unified CME 4.0 and earlier, using the command transfer-system full-consult dss command to select between blind transfers and consult transfers for the DSS under the telephony-service configuration.
If this command is enabled, a user can transfer a call when the call is in the connected state by simply pressing a speed-dial or monitor line button to select the transfer destination. The transfer action is automatically implied by CME if the service dss is enabled. This command will be very useful when you need to Park your calls very often. Create a speed-dial for the park number. Just press the speed-dial when the call is received to park the call.