DSL AT&T and has no dedicated phone line. It was a small hassle at first getting it going. But no you don't need a landline phone.
Our DSL does not have a back up dialup. It does not go down much...never for a whole day. Maybe 4 times a year for an hour or so. Sometimes it does need rebooting which is not hard.
I believe Vonage needs high speed to work (cable)
I have never tried the other voice programs so maybe someone else here will have an answer for you.
We have basic DSL and it works just fine for us. But we are not gamers or heavy downloaders. I did download some MP3s recently and they were very fast, anyway.
__________________
All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
************************************
.
Weezie looking at petunias 8.25.2017
****************************
These forums are for mutual support and information sharing only. The forums are not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider. Always consult your doctor before trying anything you read here.