OzarkEdge gave you good advice.
PhonePower is a full-service VoIP provider, in that they supply your adapter device (ATA) and they program it. (With some other VoIP providers you supply and customize your own equipment).
A similar company in that full-service VoIP category would be 1-Voip.
https://www.1-voip.com/residential-voip.php
In case you want to comparison-shop.
Please note that if you live in some kind of rural or outlying area, you might not be able to port your number. Check that in advance with your preferred VoIP company.
Also a very basic requirement for VoIP is a stable Internet connection. It does NOT need to be super-fast but it does need to have low jitter.
Your VoIP adapter (ATA) probably should be behind your Router for increased security. Ask the VoIP provider if you have questions.