Customizing  Your  Phone 
77 
DSS Keys 
There are three types of DSS keys: Line Keys, Programmable Keys and Ext Keys. Ext Keys are only 
available when the EXP50 is connected to IP phone. For more information on how to configure 
the Ext Keys, refer to Assigning the Features for Ext Keys. Details are introduced in the following: 
Line Keys 
You can assign predefined functionalities to line keys as well as define a label for a line key. Line 
keys allow you to quickly access features, such as recall and voice call, and monitor a specific line 
when the line keys are assigned with particular features, such as BLF. The default line key type is 
Line or N/A (meaning that this line key provides no functionality until being configured). The 
line keys can be indicated on three pages. 
Details are introduced in the following: 
The following figure shows an example on the SIP-T54S IP phone when assigning functionality 
to line keys located in line key 1-10, the labels of line keys are indicated on the first page.