The downside of any VoIP system using the Internet is the Internet itself.

I highly recommend this if you have a fast/stable internet provider.

Although I purchased the Telo Air, I do have an ethernet cable plugged into it for a more stable internet connection

I work from home, and unlike the other services, this works (with the phone plugged to a connected Linx).You don't have to have the best internet to enjoy the best sound quality (on both ends)