iPhone app in private beta · Gateway is open source
Your number stays home. Your calls and texts come with you.
Leave an Android phone with your SIM card at home as a gateway. Your iPhone, and your family's, can then answer calls, make calls and send texts on that number from anywhere. Everything is end-to-end encrypted; our servers can't read it.
The iPhone app is in an invite-only TestFlight beta and not yet on the App Store.
Made for
No second phone to carry, no roaming, no forwarding to another number.
You're away, your number is at home
Abroad, travelling or living elsewhere, your number still takes calls and verification codes, and people still see your number.
One number the whole family answers
The home line, a parent's number, the business line: several iPhones ring at once, and whoever is free picks up.
Both SIMs, on your iPhone
One Android phone with two SIMs brings both lines to your iPhone, with family permissions set line by line.
Unknown callers, screened first
The call assistant answers in your own voice. You read what the caller says on your iPhone, then decide whether to take over.
How it works
No account. Devices pair by QR code, and each one has its own keys.
- Install the gateway at homePut the SIM in an Android phone, install the SimNest Gateway and grant what it asks for. A spare phone, plugged in and on Wi-Fi, is ideal.
- Pair your iPhoneOpen SimNest on your iPhone and scan the code on the gateway's screen. That iPhone becomes the owner; invite family with a link or QR code.
- Head outCalls ring your iPhone, texts arrive on it, and dialling from it calls out on the SIM at home.
Calls go direct whenever they can: same network, public IPv6 on your home Wi-Fi, or a router port mapping. Only when none works does a relay pass the audio along, and it only ever sees encrypted audio.
What it does
All of this is already in the beta.
Calls
- Ring several iPhones at once, the owner first, or a chosen person first
- Calls show in the iPhone's Recents and can be answered on the lock screen
- Hand a call to family, or bring them into it
- Shows where an unknown number is from
Texts
- Feels like the iPhone's own Messages
- Copy verification codes in one tap
- Load older texts from the gateway phone by date
- Drafts wait while the gateway is offline and can send when it's back
Family sharing
- Per line: answer, call out, read texts, send texts, see contacts
- The owner can take any of it back
- Move to a new phone with the old one's approval; lost it? Use your recovery code
Call assistantOptional
- Answers unknown callers right away, or after ringing a while
- Speaks in your own voice: just read a few sentences
- Live transcript; listen in, tap a reply, or take over any time
- Voice and transcript are made on the gateway phone itself
Call recordingOff by default
- Kept on the gateway phone at home
- A space limit per line; the oldest go first
- An optional notice the other side hears when the call starts
Know before you go
- A pre-trip check: gateway, SIM, network, direct paths and battery on one page
- Told within a minute if the gateway goes offline
- Calls recover when you switch between Wi-Fi and cellular
- Home screen widgets
Our servers can't read your calls or texts
Texts, caller numbers, contacts and call logs are encrypted on the sending device with the receiving device's key. Only that device can open them.
End-to-end encrypted
HPKE (X25519, HKDF-SHA256, AES-128-GCM) with a device signature on every message. Servers and relays only pass ciphertext along.
No account
No name, phone number, location or advertising ID collected. No third-party analytics or ads.
Logs only when you say so
Diagnostic logs are uploaded only when you tap Send, never contain phone numbers or text content, and are deleted after 30 days.
See the Privacy Policy.
The gateway is open source
The gateway lives on your phone at home with full access to its calls and texts. So its code is public: anyone can check what it does, and help bring it to more phones.
| Part | Runs on | Does | Code |
|---|---|---|---|
| Gateway | The Android phone at home with the SIM | Takes over the SIM's calls and texts, encrypts them for your iPhones | Open, GPL-3.0 |
| SimNest for iPhone | Your and your family's iPhones | Answering, dialling, texts, family | Closed |
| Core service | SimNest's servers | Push, pairing, call setup, passing ciphertext | Closed |
| Self-hosted relay | Your own server or NAS | Relays encrypted audio when a direct path fails | Open, GPL-3.0 |
For your own tools: MCP
The gateway has a built-in MCP server. Your AI tools can read and send texts, place and answer calls, and talk with the caller in text while the gateway transcribes and speaks. Authorised on the gateway, rate-limited by default.
Run your own relay
Run a relay with Docker on your own server or home NAS, and your calls never pass through SimNest's relay. How to deploy
Where things stand
Written down here so you don't find out after installing.
- The iPhone app is in beta, installed by TestFlight invitation, and not yet on the App Store.
- The gateway is released on GitHub and Gitee. It works together with the iPhone app.
- The gateway needs Android 12 or later. Verified: Redmi Note 11 5G (Android 13); Huawei Mate 40 RS works with limits. Other phones are untested.
- The gateway phone stays plugged in and online. First-time setup turns on Wireless debugging, which the gateway uses to carry call audio.
- Most dual-SIM phones handle one call at a time: while one SIM is on a call, the other's callers get a busy signal.
- MMS content isn't forwarded, only a notice that one arrived. For emergency calls, dial from the phone in your hand.
Questions
How is this different from call forwarding?
Forwarding needs another number to answer and can't bring your texts. SimNest uses the SIM at home itself, so people you call still see your own number.
How is this different from eSIM or roaming?
No new SIM, no roaming. The number stays on the physical SIM at home and works wherever you have internet.
Does the phone at home have to stay on?
Yes: plugged in, online, with the gateway running. A spare Android phone dedicated to the job works best.
What's the call quality like?
It depends on the network at both ends. Direct paths have the lowest delay; a relay adds a hop. Your iPhone shows which one a call is using.
Can your servers read my texts?
No. They only pass encrypted content along; the keys stay on your devices.
Why is the gateway open source but not the iPhone app?
The gateway holds the call and text permissions of your SIM, so you should be able to check what it does, and others can help support more phones. The iPhone app and core service are how we keep the product going.
How do I join the iPhone beta?
It's invite-only for now, with limited places. We'll say so here when it opens up.