Use the server geographically closest to your physical location. Closer servers mean lower latency, which translates to better call quality with less delay and echo. A server further away will still work, but proximity is the right starting point.

Your device registers to the chosen server as well as your DID (phone number). You will notice that your DID also has a Point of Presence (POP) setting. Both must be set to the same serveur. If they don't match, inbound calls will not reach your device. Set your DID Point of Presence under DID Numbers → Manage DIDs → Edit.

Latency is the round-trip travel time of a data packet between your network and the VoIP.ms server, measured in milliseconds (ms). For voice calls, low latency means natural conversation with no noticeable delay. High latency causes the characteristic "talking over each other" effect.

Acceptable thresholds:

• Under 150 ms: Good quality, delay is imperceptible
• 150–300 ms: Noticeable but tolerable
• Over 300 ms: Unacceptable for voice calls

To measure latency to a server, ping its hostname from your computer or network:

ping atlanta.voip.ms

Run this for two or three candidate servers and pick the one with the lowest and most consistent response times. High variance (jitter) is as problematic as high latency. It causes choppy or robotic audio.

Latency is primarily determined by physical distance and your ISP's routing. If latency to the closest server is unexpectedly high, try the next nearest city. Your ISP may route traffic inefficiently to certain destinations.