We used Vonage for 1-2 years. We did use our same phone number.
If you have specific questions I can ask my dh, just not sure what you want to know.
We did experience some choppy phone signal. Sometimes the phone conversation would chop up like a cellular phone. Bearable but annoying at times. But for the money it saves, may be worth it!
he and my SIL love Magic Jack. It works well for them when they go south and want to phone home. And their friends phone them on their Magic Jack number. It turns up on a computer and then they can phone back (if they aren't home to take the call). It's worth investigating.
You can also use Skype for phone messaging and not just video calls.