tward
VOIPO around $6.20 a month ($149 for 2 years)
Actually "Voipo" is 149 PLUS 36 (the additional 36 is for taxes and fees) for a total of 185.
Which is still quite good.
They are a plug-and-play company that provides an ATA for you.
Some people like having plug-and-play, other people prefer to be able to use their own equipment such as IP phones.
Often the companies such as Callcentric and VoIP.MS where the customer uses their own equipment, have more advanced features overall for IVR, call blocking and blacklisting, and so forth.
Many/most of the companies have added taxes and fees, and you have to drill down to look at that.
The Boomer VoIP company Vonage was among the worst, even charging fees that helped pay their own lawyers This is the Vonage "Regulatory, Compliance and Intellectual Property Fee" charged at about 3.50 per month per line. Crazy.
The 3 companies you named are all well-established and are good.
My main provider for many years (for both business and home) is Callcentric.
They've provided me excellent features, service, and value.
With Callcentric you do supply your equipment---and I prefer that being that I can use advanced IP phones that work better with features such as multiple simultaneous calls and which have better connectivity overall.
With Callcentric you choose your outbound and inbound plans individually, so there is a lot of flexibility.
https://www.callcentric.com/products/
https://www.callcentric.com/features/
So a question is looking at VoIP companies overall: How many minutes do you typically need each month of EACH type (outbound and inbound).
By the way with Callcentric there are no added fees or taxes: 911 cost is included in most of the outbound minute plans, no Federal USF tax, no other fees except small one-time startup fee and (only for NY State residents) there is some NYS sales tax.
To make the best pick for your needs, look at the whole picture, not only at price.