DECT is simply a standard used for wireless communication, it can be used for many things but phones are the most common by far, it stands for Digital Enhanced Cordless Telecommunications BTW
Because it is a standard then in theory you should be able to "pair" any DECT handset with any DECT base station, though you may not get some of the advanced features.
so short answer, yes you should be able to pair one of your existing handsets with a new base station regardless of who makes it.