← All guides

How VoIP Calls Reach Landlines and Mobile Phones

Follow a browser call from microphone capture and WebRTC through carrier routing and PSTN termination to an ordinary telephone.

Reviewed by Voxa · Updated 2026-08-27 · 9 min read

Direct answer

A browser VoIP call captures your voice, encodes it into digital audio, sends it over an encrypted WebRTC media connection, and hands it to a voice carrier. The carrier selects a route into the public switched telephone network (PSTN), where a terminating carrier rings the destination landline or mobile phone.

1. The browser captures and encodes audio

After you grant microphone permission, the browser samples your voice and encodes it with a voice codec. WebRTC manages real-time audio, echo handling, packet timing, and negotiation between the browser and the communications infrastructure.

2. Signaling sets up the call

Before media flows, signaling authenticates the account, validates the destination, applies balance and fraud controls, and asks the provider to create the outbound leg. Signaling describes how the parties can communicate; it is distinct from the audio itself.

3. Audio crosses the internet securely

The browser leg uses standard encrypted web and WebRTC transport. Network latency, packet loss, jitter, Wi-Fi congestion, and device performance can affect this stage. A stable low-latency connection matters more than headline download speed.

4. A carrier bridges VoIP to the PSTN

The voice provider converts and routes the internet call toward a carrier capable of terminating calls in the destination country. Routes vary by destination, number type, regulation, capacity, quality, and wholesale cost.

5. The destination carrier rings the phone

The final carrier delivers the call to the mobile network or landline exchange serving the number. From the recipient’s perspective, the phone rings normally. The receiving network may alter or suppress caller ID, so no provider can guarantee identical presentation on every route.

Where call quality problems originate

One-way audio often points to browser permissions or network filtering. Choppy audio usually indicates packet loss, jitter, or congestion. Echo may come from speakers feeding a microphone. Distortion or delayed connection can also originate in downstream carrier routes. Separating these stages makes troubleshooting faster.

Security boundary

The browser and VoIP infrastructure use encrypted transport. Once a call is bridged onto ordinary telephone networks, it is not end-to-end encrypted across every carrier. This is an important distinction between transport encryption on the internet leg and end-to-end encryption between two app users.

Frequently asked questions

What is PSTN termination?

PSTN termination is the process of handing a VoIP call to telephone carriers that deliver it to the destination landline or mobile network.

Why can VoIP call quality change by destination?

Different destinations use different carrier routes and networks. Internet conditions affect the browser leg, while downstream carriers affect connection time and final-leg quality.

Are browser-to-phone calls end-to-end encrypted?

No. The browser media leg is encrypted, but a call that enters the public telephone network is not end-to-end encrypted across the complete route.

Ready to make an international call?

Check the current destination rate before dialing.

View rates