Unit 2A, 17/F, Glenealy Tower, No.1 Glenealy, Central, Hong Kong S.A.R.
Privacy policy
What SimTether holds, and for how long
There is no account here, so there is very little to hold. This page lists every record the service keeps, why it exists and when it is deleted, including the one part we cannot protect.
In short
Four things, before the detail
If you read nothing else on this page, read these.
SimTether carries the text messages your own SIM receives to the phone you are carrying, and sends your replies back out from that SIM. To do that it needs your messages for as long as it takes to deliver them, and almost nothing else.
No account
You never give us a name, an email address or a phone number. Your iPhone makes a key pair when you install the app, and that key is your only identity here.
Keys, not passwords
A device is enrolled by scanning a code off the phone at home. There is no password to steal and no login to reset, and every request the app makes is signed by the key on it.
Deleted on delivery
A message waiting for you is deleted the moment your iPhone collects it. One that is never collected is deleted after seven days. A reply is deleted as soon as the phone at home reports that it went out.
Never sold
We do not sell, rent or share anything here, and there is no advertising, no profile and no tracking in either app. The only lasting record of traffic is a daily count with no names in it.
The limit
We can read a message while it passes through
The phone at home has no encryption of its own, so it hands each text to our relay in the clear over an encrypted connection. The relay seals the message before it writes anything down, and it holds the key that seals it. So what sits in the database is safe from anyone who steals the database, but it is not safe from us.
This is not end to end encryption and we do not call it that. If the people running the service are part of what worries you, SimTether is the wrong tool, and we would rather say so here than let you find out later.
True of the network too
An SMS crosses the mobile network in the clear long before it reaches the phone at home. Your operator, and anyone with lawful access to it, sees every message you receive whether SimTether exists or not.
The records
Every row the service keeps
This list is the database, written out. There is nothing behind it.
Messages for you
The sealed text of a message waiting to be collected, filed under a fingerprint of your public key rather than a number or a name. Deleted the moment your iPhone collects it, and swept after seven days if it never does.
Messages you send
The text of a reply and the number it is going to, held in the clear because the phone at home cannot decrypt anything before it types the message into the radio. Deleted the moment that phone reports it went out, and expired after one hour if it does not.
Your device
The two public keys your iPhone generated, the label you gave the device and which phone at home enrolled it. No private key of yours is ever sent to us.
The phones at home
An identifier each Android phone chooses for itself, the name typed into it and when it last called in. This is what tells four SIMs apart.
Push token
The token Apple issues so we can wake your iPhone. The push itself carries no message text, so Apple learns that something arrived and nothing about what.
Pairing codes
A hash of the single use code behind a pairing QR, never the code itself. It expires two minutes after it appears and cannot be spent twice.
The sealing key
One key pair, held by the service, that every message is sealed from. It is the reason we can read a message in transit, and it is stated in the section above rather than hidden down here.
Abuse limits
Hashes of recently signed requests, so a captured one cannot be replayed, and hourly counters behind each rate limit. Both are swept nightly.
Traffic counts
One row per day per counter: a date, a name and a number. No phone number, no message, no device and no hour. Kept indefinitely, because a count of messages carried is a business fact and cannot identify anybody.
This website
The site is a separate system
simtether.com is a set of static pages. It holds nothing about your messages, because it is not connected to the relay at all.
Visitor measurement
We use Cloudflare Web Analytics, which sets no cookies and builds no profile: it counts page views and referrers and cannot follow you to another site. There is no consent banner because nothing is stored on your device.
Contact and newsletter
If you write to us or subscribe, the name, email address and message you type reach our own internal channel and are kept so that we can answer you, and for a subscription until you ask us to stop. They are never sold or handed to an advertiser.
Hosting
The site and the relay both run on Cloudflare, and the relay's database is stored in Western Europe. Cloudflare processes requests on our behalf and keeps its own short lived operational logs.
Your choices
What you can do about any of this
Most of it you can do yourself, from the app or from the phone at home, without asking us.
Delete everything from the app: leaving takes your device record, every message still waiting for you and your push token with it.
Unpair a device from the phone at home, which stops it receiving anything from that SIM immediately.
There is no account to close and no export to request: the archive of your messages lives on your iPhone, not on our server.
Ask us anything about this page at [email protected], and we will answer within one working day.
If you are in the EU or the UK you can ask for access, correction, erasure or restriction, object to processing, and complain to your data protection authority.
Who is answerable
The people behind the service
Operator
HK Managed Services Provider Limited, Unit 2A, 17/F, Glenealy Tower, No.1 Glenealy, Central, Hong Kong S.A.R.
Contact
[email protected], Monday to Friday, 09:00 to 18:00 Hong Kong time.
Where the data is
On Cloudflare's network, with the relay's database in Western Europe. Messages leave it as soon as they are delivered.
Last updated
27 August 2026.
Changes
If this policy changes in a way that affects what we hold or for how long, we will say so on this page and in the app before the change takes effect.
SimTether has not been independently audited, and an SMS crosses the mobile network in the clear long before it reaches the phone at home. We protect everything after that point, and we say so plainly rather than calling it end-to-end encrypted.
Get in touch
Tell us what you need to reach
One SIM or four, one country or three: describe the situation and we will tell you honestly whether this solves it.
Head office
Unit 2A, 17/F, Glenealy Tower, No.1 Glenealy, Central, Hong Kong S.A.R.
Email us
SimTether
SimTether puts the texts from the SIM you left at home on the phone you carry, and lets you answer from the same number. Free, with no account.
Contact
Unit 2A, 17/F, Glenealy Tower, No.1 Glenealy
Central, Hong Kong S.A.R.
Monday to Friday, 09:00 to 18:00 HKT
Occasional updates
One short email when there is something real to say, such as the app reaching the App Store. Nothing else.
SimTether is software for reaching your own messages. It is not an operator, it does not issue numbers, and it does not port anything.
© 2026 HK Managed Services Provider Limited. All rights reserved.