I already have voip... is asterisk for me?

I have a fibre optic connection (rj45 port) in my wall.
My router plugs into it.
My primus.ca (dlink) gateway plugs into my router.
My phone plugs into my gateway.
Everything works fine…
Is asterisk for a telco pots connection only?
We used to have a pots line but now we just have a phone plugged into it so it rings when someone buzzes our apartment.

Asterisk is not for POTS only. It is a PBX, so you need to determine if you need some PBX functions (IVR, voice mail, follow-me, find-me, etc.) at home - or some of more exotic functions Asterisk can help produce. You may want to browse the free O’Reilley book’s Chap. 11.

Thanks. I called Primus.ca and the tech said I can set up a pbx.
All they would do is set the phone to keep ringing so my pbx would take over. Thanks for replying!