Extension Status on Speed Dial Button

i know I’ve seen or heard of this before but i for got what it is called.

I want to create a speed dial button on my phone and change the icon/light it up if that ext is on the phone.

is this a setting on freepbx or on my phone or both?

i am using a Yealink T48G and Yealink T22P
Asterisk (Ver. 1.8.25.0)
FreePBX 2.11.0.43

It is called a hint.

Many hints already exist.

in the Asterisk CLI:

core show hints

You need to tell your phone to subscribe to them.

Thanks, Found it!

Its called a BLF (Busy Lamp Field).

All i had to do was add a DSSKey and make it type BLF the value is the extension.

I also found an article that says the BLF feature can be used to see if settings like follow me are active.