Busy Line indication

I have 6 SPA942’s and a few AAstra 57i’s and 4 Snom3’s
On the phones that I can do it on, say the SPA942’s and the Aastra’s how can I have a busy line appearance ?
i.e. light goes red when the line is busy …?
or light goes red when an extension is busy if you have one button > one extension ringing enabled.
I realise busy line and busy extension are different things…