How do you stop Digits from ringing on a tablet when an incoming phone call comes?

Hello to the community

I installed the DIGITS app on several devices, but I only want my old phone to ring when an incoming call is received (Not my main phone).

I do not want my main phone rings for any incoming call that comes through the digits! How can I stop it? But I still want to see the text messages and voicemails and call logs from DIGITS. I just dont want my phone rings for the DIGITS incoming calls.

Thank you,