If you enabled RTT phone calls, you can choose to make an RTT call.
Safari: Click a phone number on a webpage, then click Call.
Mail: Place the pointer over a phone number in an email, click the pop-up menu , look for a phone number in the notes, then click the number.
On your Mac, when a notification appears in the top-right corner of the screen, do one of the following:
Accept an incoming call: Click Accept.
If the person calling you has enabled RTT for the call and you want to answer it that way, click RTT.
Decline a call: Click Decline.
Tip: If the call came from someone you don’t want to receive calls from, you can next to Decline, then choose how long you want to wait to receive a reminder. When the time comes, you receive a notification — click it to view the reminder, then click the link in the reminder to start the call.
If your Mac has a (or use the Use the Touch Bar on MacApple Support article: If FaceTime isn’t working on your Mac