Open Source - How to configure a second line for a Digium phone

Setup > Digium Phones

Click Drop-down menu, select Assigned Phones and Extensions

Modify extension by clicking yellow pencil

Select the Add button

Enter the extension number you wish to assign in the Add System Extension field

Or, search using the magnifying glass and Select extension from list

Save assignment as shown

System now shows Line-key 1 (main extension) as 401 in this example, and 402 as the Line-Key 2 (secondary extension)

Digium phone will display the two line keys (401 and 402, in this example) after the phone receives an update from the server. Or you can simply reboot the phone.