I have tried to make a generic description of services and hardware to which I am familiar with. This is not a complete list by any means and there are probably hundreds of VOIP providers (some operating under multiple names).
The discussion was meant to help you begin to grasp the myriad of options available to you and to get you thinking about whether VOIP is for you and how you might use it.
Some options and configurations are pretty much no-brainers and will work out of the box. Some require a bit more technical work on your part. Some may require lots of technical help or the desire to really get into the nuts and bolts.
If I was setting up a system for Mom and just wanted something to work out of the box, I might use OOMA and pay a bit upfront and a small fee per month.
With a small amount of technical skill, perhaps an IP phone or old style ATA and a VOIP account somewhere, or an Obi with a VOIP account. Many adapters allow you to configure one or more of the many VOIP services.
For more control of call flow, I might go with Callcentric or VOIP.MS and an IP phone or Obi.
To really play around, try a RaspberryPi with FreePBX and NerdVittles (yes it also has a hook to use GoogleVoice as a free VOIP provider).
GoogleVoice has free telephone numbers in many states.
Callcentric currently offers a free inbound number in New York State.
VOIP.MS has reasonably priced telephone numbers in the U.S. (perhaps $1 to $1.50 a month) and reasonable per call prices in the U.S. Canada and overseas).
VOIP.MS also make is easy to create sub-accounts and manage them from one location, allowing you to create accounts for your relatives and let them prepay for their calls via paypal (for example). You become a little phone company. Some or all of the sub accounts can show the same telephone number in the called person’s caller ID.
Although I am not sure I would use GoogleVoice in a business setting yet, Callcentric or VOIP.MS would seem to work fine.
A U.S. toll-free number might cost $1 a month with no calls and utilizing a VOIP provider might cost you a couple cents a minute when someone calls you. You do NOT need an outbound toll free number; just choose a cheap or quality VOIP provider to complete your calls.
International call price comparison for a call from the U.S. to London is:
GoogleVoice: 2 cents per min
Callcentric: 2 cents per minute
VOIP.MS: 7/10s of a cent per minute (the winner for this example).
My Verizon cell phone rate: 65 cents per minute (the loser)
By turning off my cell phone voice and using a data plan or wifi connection, that Verizon cell phone rate drops from 65 cents a minute to 7/10s of a cent if I have a VOIP.MS account and use a software app like Zoiper on the phone to connect to my Voip.Ms account.