It depends on what you mean, Asterisk is a software for creating virtual PBX systems on a variety of platforms. A lot of V-PBX software is derrived from Asterisk. Overall though, it seems like a great software package for this type of purpose and they seem to have a strong and systematic release pattern for updates. It's used world wide for PBX systems and is for the most part open source, so it doesn't seem like it's going to not be supported anytime soon.
