Not sure what technical term is.
But can you have multiple phones logging into PBX as same extension?
My example is I have a Desk-phone, Then I have a softphone for when remote. So rather than have a softphone extension different to my general desk-phone. Can you just connect with SoftPhone with same credentials even though the phone is connected on my Desk at office.
I run PBXact
I have tried it but get mixed results. So not sure if there is a setting somewhere to allow it.