Do you want to be able to have 2 or more people in your home to be able to talk to the other party or to be able to have 2 or more people be capable of talking to different parties at the same time?

I might be wrong, but I haven't seen a system that lets you use two handsets at once for a phone call; only when using them as an intercom with each other.

my AT&T 9100 (old) does let you talk to the caller with more than one handset.

It's nice when someone calls, and it's for another person in the house,
and you holler to that person to pick up the other phone....

I don't believe that any of those newer multi-phone DECT 6.0 packages allow multiple phones to be used at the same time. The remote units all talk to the base unit to get their connectivity.