Button to toggle call recording on/off

Hi I have Yealink t42s phones and need to put a button on the phone to toggle call recording on/off. I know I call *1 during call but users are asking for a button.

Is this possible?

you should be able to do a BLF with a value of *1

I have Type: BLF Value: *1 Label: Record Line Extension: What do i use for extension?