Aastra Telecom IP Phone - Manual (Page 106)

98 Model 57i IP Phone User Guide
Line Keys and Softkeys
5. In the "Line" field, select the line you want to apply to this softkey.
Valid values are 1 through 9.
6. If configuring a softkey on the Bottom Keys, in the state fields, check (enable) or
uncheck (disable) the states you want to apply to this softkey.
7. Click to save your changes.