Hi beepbeep, To make calls and send messages on a device other than your phone, you'll need to add the same Samsung account to both the phone and the tablet. Next, navigate to Settings and search for and select Call & text on other devices on both the phone and tablet. Turn the feature on by tapping the switch. The connection will occur automatically.
Now you can make and answer calls or send messages on your tablet.
Note: You can transfer all your messages from your phone to your tablet using Smart Switch.
My S8 phone does not have Call & Text anywhere - I have Sprint/T-Mobile which may be the problem. I am signed into the same Samsung account on both devices. The Tab S6 comes up with a QR code immediately when I attempt to link and it tells me to take a picture of the QR with my phone. On the phone, the QR code is translated into string cmc://setting? ........ It copies it to Samsung Notes. Both devices are up to date and the S8 is running Android 9 and the Tab S6 is 10 I believe. I'm assuming this is some type of phone firmware correction which does give me some apprehension. I've done something like this on an old S4, but the S8 seems to have a completely different interface and I do not see a way to utilize the cmc:// string
