Can a tablet actually replace a phone?

I seem to remember, maybe two years back, a buddy mentioned you could actually use a tablet just like a smartphone if you popped a certain kind of card into it.
The idea was that the tablet would handle calls and texts just fine, like any regular cell
Is there any truth to that? And if so, what kind of SIM card am I looking for?

You'll need a SIM card for that, which means you have to make sure the tablet actually has a SIM slot built in, because honestly, not all tablets come equipped with one.

And even then, you can't just assume every tablet with a SIM slot is actually going to support voice services.