what would you say is the cost range is for a small company using VOIP VS large company?
please include the cost of devices(IPphones,ethernet cables,or any services needed to use VOIP on a small or large companies network)
That is just a matter of scalability.
It is always calculated on a “per user” basis. Obviously, large companies have more users and thus benefit from “Volume Pricing”. Thus, on a per user basis, large companies will pay less due to volume pricing and economy of scale.
There are some very cheap alternatives to IP phones etc. if you are deploying in a small business setting. I highly recommend you take a look at virtual PBX systems such as eVoice, RingCentral and Nextiva you can compare pricing and features at http://www.voiprater.com/pbx.
As for larger deployments, it can cost thousands of dollars to setup a system with an Asterisk server, expensive routers, cabling etc. It basically comes down to the size and scalability. A system such as the virtual PBX’s mentioned above are great for small businesses with up to 10 people and allow you to forward calls to an ext. but ring multiple lines at once, forward to a cell phone and more.