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With the Sinch Voice API or our Voice SDKs, you can easily add crisp HD quality VoIP calling using WiFi calling or PSTN origination and termination to your app. Add voice calling for better app engagement, stickiness, and increased user retention. Pay as you go. No additional monthly fees. No commitments.


HD Voice Codec

Sinch improves upon the HD Opus Voice Codec with automatic and adaptive configuration to adjust latency and audio quality according to network speed to optimize sound. Using FEC (forward error correction), we send redundant data so that the receiver only recognizes the data portion that is error-free

PSTN Routing

Sinch has direct connections with aggregators to maximize routing for the best quality connections at all times. Monitoring traffic 24/7, we engage in early detection of connection issues or reduced quality and re-routes traffic accordingly, ensuring the best in quality

Call Setup Speed

With low latency call setup, the receiver to be notified under a second of an incoming call when using our active connection technology and in 1-3 seconds using push notifications. This is superior to standard protocol for VoIP, which results in call setup times of 2-5 seconds


Sinch offers the most competitive and transparent pricing. No hidden fees. No commitments. Pay as you grow. Check out our pricing page for details.



It's this easy

android Created with Sketch. Android

apple Created with Sketch. iOS

CallClient callClient = sinchClient.getCallClient()
Call call = callClient.callUser("John");

id callClient = [sinchClient callClient];
[callClient callUserWithId:@"John"];


Getting started with the Sinch Voice SDK is simple with our extensive documentation for each platform and a variety of tutorials and sample applications available.


DID Management

Manage your DID rentals in the dashboard with auto-renewal for ease of maintenance and no service interruptions.

Voice Encryption

All voice streams operated through Sinch are encrypted end-to-end.

Fast Connect

Sinch technology significantly reduces call setup times by 50%

Push Notifications

Send Push Notifications directly from the SDK for seamless communication in the foreground and background.

Cross-Platform Support

The Sinch SDK is currently available for iOS, Android and Javascript platforms and Sinch back-end services are exposed over REST APIs, primarily for back-end to back-end integration.

Reach Global Markets

Reach markets in every country across the globe by enabling users to contact their friends and family.

CUSTOMER USE CASES Discover More Customer Use cases >

Tango is the all-in-one social networking app that gives you unique and meaningful ways to interact with your friends and family. They turned to Sinch for app to phone calling.

“We tested the market thoroughly, and we chose Sinch because of their high quality product, ability to scale, and excellent customer service”

Eric Setton
Co-Founder & CTO

Rebtel provides international calling apps for iPhone, Android, Windows Phone and PC. App to Phone calls are an integral piece of the Rebtel product, powered by Sinch.

“Sinch gives us a mix of the fantastic quality and solid reliability Rebtel needs”

Anna Alenius-Mathson
Head of Communications