Using phones that offer multiple line display, users can hold/pick up the line simply by using the line key buttons. When you want to transfer a call or pick up a call at a different location, simply put the caller on hold and then pick up from a different phone by pressing the line key. Also, by monitoring the line usage, a colleague or assistant can answer incoming calls when you're on another call. 

This feature is useful when you have a main business number that can be answered by multiple people. You can set a group of extensions to share the number and then display the line status at the phone's line key display. 

At the Brekeke Wiki page, please find the instructions on how to set up Brekeke PBX and SIP phones to have the SCA feature.