Welcome to the forums.
I find your post a bit unclear. In the thread title, you say you want to build an intercom, but in the post you want to build a pager. Either (or both) is certainly possible. What sort of programs do you intend to use? A web browser? E-mail? IM clients? VOIP?
And, by the way... Some of us are old, cranky and sticklers for terminology. There is no Pi2B+. There is a Pi2B model, a Pi3B model, and a Pi3B+ model. (and, of course some older versions, but if you're new to the Pi you are unlikely to be planning to use any of them.)
Any of those three versions of the Pi could do what you want. Depending on what exactly you're planning to do, and how you plan to do it, one or more models nay need added hardware connected.