You need a stable internet connection. It doesn’t need to be fast, but it must be stable. SIP services can carry over most data plans, and home wifi networks. For connectivity, you need 500kbps for speed, and less than 100ms ping. As you can see, you don’t need something powerful, but being that you have to have less than 100ms, it must be stable. This is so calls can carry through the internet without hiccups, or delays. Obviously, you would need a stable internet connection as long as you would want to use SIP services.