VoIP meand you can eliminate most all of the voice centric hardware that costs bundles to own and maintain. Ofcourse, you have to put in new hardware to to support voice. But since it is network traffic, it is easier to manage and maintain. Keeping voice “on-net” can save bundles of cash too.
If you have a service provider put in a big voice pipe, you don’t have to have hardware other than networking stuff this is probably already there. Then you get all the cool features and just pay a monthly fee per phone number. You can get new services and advanced feature with no upfront cost. Since a PBX will cost around 30 – 500 grand (and more), then maintenance and the fact that no one knows how to manage it, you spend a bunch of cash a year to have service and support.
I really think the entire worrld must go to VoIP, especially from a service provider. I think this because I work for a company that is pretty much the leader in this arean and I will make a boatload of dough.