3NUM Labs
Private calls and texts, on the phone number you already have.
Today's phone network was designed to be listened to, and a number can be stolen with one call to a carrier.
3NUM Labs builds ATSMS, an open standard for private calls and messages. Any company can offer service on it, the way any company can offer email, so no one owns the network. Not even us. And it still reaches every phone.
The problem
The phone network was built to be listened to.
The wiretap door never closes.
Carrier networks carry interfaces for court-ordered wiretaps. In 2024 the Salt Typhoon intrusion used those same systems to listen to calls and read texts at several US carriers. The interface cannot tell a court from an attacker.
A phone number can be stolen.
A SIM swap moves your number to someone else's phone with a phone call to a carrier. Every account that resets a password by text message goes with it.
Nothing proves who is calling.
Caller ID and SMS carry no proof of origin. That is why phishing works: a real message from your bank and a fake one look the same, because neither can prove where it came from.
None of this can be fixed inside the phone network. It has to be replaced from underneath, and it has to keep reaching the old network while that happens. That is the whole design brief.
What we build
Three parts. We build the first two in the open. Anyone can be the third.
ATSMS: private messaging and calls
An open standard for end-to-end encrypted messages and calls between people who sign in with an AT Protocol identity, the same kind of account Bluesky uses. Any app can add it without touching phone numbers at all.
Phone numbers that belong to you
A number on the network is tied to your identity, not to a carrier's database, so it cannot be handed to a stranger. Gateways connect to the ordinary phone network so you can still call anyone.
Companies that offer it
Operators run the servers and sell the service: plans, apps, call screening. Haiven Mobile is the first. Everything a second company needs to do the same is published.
Better than what it replaces
What changes when the network is open and encrypted.
Each claim carries its limit. We would rather you read it here than find it yourself.
Private by design
Every call and message is encrypted end to end. Keys change with every message, so someone who steals a key today cannot read yesterday, and the group locks a thief out again as soon as it re-keys. Direct messages and groups get the same protection, so neither is the weak one.
LimitThe cryptography has not had an independent security review yet. That review is a requirement before this carries traffic that matters.
No company in the middle
Most encrypted group chat still relies on one company's server to keep everyone's changes in order. ATSMS does that job inside the protocol, so no company sits between you and the people you talk to.
LimitComfortable to about 25 devices per group. Larger groups add a shared drop-box, called a group relay, which is a published proposal and not yet a finished part of the protocol.
Your number cannot be swapped away
A number on the network belongs to you through keys only you hold. If a carrier is tricked into moving your number, the thief gets a number that no longer reaches you or your accounts, instead of your whole life.
LimitThis protects who can reach you on ATSMS. A service that still sends codes by ordinary text message is only as safe as the carrier that delivers them.
An identity that is yours, not ours
You sign in with an AT Protocol identity, the same kind of account Bluesky uses, not a row in our database. Switch apps and your conversations come with you, because they were never the app's to hold.
The server in the middle cannot read anything
Messages travel in sealed envelopes. The server that passes them along never learns who is talking to whom.
LimitThe server still sees the connecting IP address, timing and volume. Someone watching it long enough could learn patterns from that, and we do not defend against it yet.
Still reachable from any phone
When both sides are on ATSMS, the call or message is encrypted end to end. Otherwise it crosses to the ordinary phone network through a gateway, and the app tells you which is happening.
LimitInbound calls from the phone network have been live since September 2026. Text-message bridging is designed and not yet built.
Open source
Everything you need to run it, in the open.
The protocol, the reference nodes and the reference clients are published under the Apache-2.0 license in the 3numlabs GitHub organization. The official specifications live on the protocol's own site, atsms.at.
A proof of concept, not a product. Nothing is published to npm, the cryptography is unreviewed, and the gateway code is not yet public.We publish what we know is broken.
- Apache-2.0
3numlabs/atsms
Encrypted group messaging on AT Protocol identities, with no company in the middle. Specifications and TypeScript reference implementation.
- Apache-2.0
3numlabs/atsms-worker
Reference relay for ATSMS: store-and-forward for sealed envelopes on Cloudflare Workers. Carries bytes it cannot read.
- Apache-2.0
3numlabs/atsms-demo
Browser client for ATSMS: encrypted DMs, groups and calls, using the Bluesky account you already have. A proof of concept.
- Apache-2.0
3numlabs/atsms-cli
Terminal client for ATSMS: a small command-line app over the @atsms/client SDK, short enough to read in one sitting.
Operators
Built for many operators, starting with one.
Haiven Mobile, owned by 3NUM Labs, is the first company selling phone service on ATSMS. Everything a second company needs is published, because a network with one operator is not a network.
Haiven Mobile
Your Safe Place to Talk.
Calls and texts without the junk; encrypted between members; a number that cannot be SIM-swapped.
haiven.mobile →
Operator · nextThe next one
What an operator runs, how a company gets accredited, and where the playbook stands. We would rather hear from a second operator early than polish the playbook in private.
Become an operator →
Articles
Latest from 3NUM Labs
Your Private Messages Should Belong to You - Now They Can
Private group messaging that belongs to you, not to an app, on the AT Protocol identity you already have.
ATSMS Group Chat: End-to-End Encryption Without the Lock-In
Encrypted groups with no server ordering anything, built on BeeKEM, published with their open questions.
Introducing ATSMS
End-to-end encrypted messaging and calls for the AT Protocol identity you already have.
Build on it, offer it, or check our work.
The specifications, reference nodes and clients are public. If you build apps on AT Protocol, run telecom infrastructure, or review cryptography, we would like to hear from you.