Enterprise mobile privacy platform

We believe the software you run should serve only you. An app should be your agent. It should protect your interests above all others. That’s how we write software. That’s what Silent Phone does. And that’s why our technology protects your business better than anything else on the market.

Our users own the keys

Silent Circle is the world leader in end-to-end encryption and authentication. Your calls and messages never leave your device unencrypted. Your private keys never leave your device at all. No one but your intended recipient can decrypt your traffic, not even us.
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Keep out the man-in-the-middle

Our unique Security Words put you in control of your own security. The words are computed independently on each device. If they match, you can be absolutely certain no one is listening in.
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Trusted by companies and government agencies around the world

Privacy-first platform

If you’re not paying for an app, you and your data might be the product really being sold. At Silent Circle, we keep things simple. Our customers are our customers. Our product is ensuring privacy.

No backdoors

The software you run should serve only you. We build products that keep out those who would do you harm. We’ll never open that door. Our products have no backdoors.

Peer reviewed

Our core cryptographic protocols have been published and have stood the test of time. Some are standards that have been published by the IETF.

Built on a fundamentally different protocol

Silent Phone calls among your team members are secured using ZRTP. The protocol was developed by Silent Circle founder Phil Zimmermann. The standard was published by the IETF in 2011. It’s widely recognized as the most secure telephony standard ever developed. With Silent Phone, you can talk with someone a continent away as securely as if you were standing in the same room.

Pure peer-to-peer key agreement

How does peer-to-peer key agreement protect my team?

Peer-to-peer key agreement allows two parties to communicate privately while keeping all keys on their devices. This technology prevents hackers, competitors, telecom providers, rogue governments, and others from eavesdropping on your team’s discussions.

Perfect forward secrecy

What is forward secrecy?

If your device is stolen by bad guys who have been intercepting your encrypted traffic, you don’t want keys stored on the device to allow them to decrypt previously sent calls or messages. We make sure that’s never possible.

Protection against MITM attacks

What is a MITM attack?

A man-in-the-middle (MITM) is a bad guy who inserts himself into your conversation without your knowledge. To each party, he pretends to be the other legitimate party. Typically he relays the traffic from one party to the other while listening in.
We stop these man-in-the-middle attacks at multiple levels. First, we ensure your device is connected securely to our (and only our) network using TLS and certificate pinning. Then we make sure you’re securely connected with the other party using our Security Words and key continuity.

Enterprise-grade 256-bit security level

How many bits long are your keys?

Our products are designed to provide a 256-bit security level or better. To break this security level, an attacker would need to perform a physically impossible number of calculations (2^256).
All keys used in Silent Phone are 256 bits long or longer.
That said, it’s important to look beyond key size when evaluating the cryptographic strength of a product. While having enough bits is an important baseline, premium security products like Silent Phone set themselves apart with their advanced key management.

Key continuity and post-quantum resistance

How does key continuity protect my business?

Once you establish a secure connection to another party, that connection only gets more secure with time. The security of new connections builds on and strengthens the existing security. That’s key continuity.
In the future, quantum computers may be able to break today’s public/private key encryption systems, but they’ll never be able to break the kind of strong symmetric encryption we use in Silent Phone. Key continuity helps symmetric encryption carry more of the load. That helps to protect your traffic today from quantum computers tomorrow.

Security without a PKI

What is a PKI?

Trust, who to trust, and how to extend that trust is the main problem in security. A public key infrastructure (PKI) creates a central third-party repository of trust and says, “trust us and anyone we say to trust.”
We think that’s fragile. Silent Phone is built with a peer-to-peer trust model. Using our Security Words, you establish a strong security association with and only with your trusted counterparties. No third-party can override that trust. Not even us.

The best call quality in the business

How good are the calls?

Security only helps if you can hear the other party. Our careful engineering ensures your calls are always crystal clear. We’ve built a global network so that no matter where you are in the world, you’ll get the best, highest-quality audio and video possible.

No logging

We don’t log the history of calls or messages between users. Most companies log and store everything “just in case.” We know that no good comes from keeping more data than is absolutely needed. Data not stored can never be lost or compromised. Your company’s data is yours. We don’t want to hold any more of it than we need.


We keep things simple. Your data is your own. We never see the content of your conversations. We never touch your private keys. Our software works for you and only you.