SMS problems
SMS not working? Confirm the destination format, device support and signal. A data-only device may not expose SMS controls even if the service supports it.
Check it in this order
- Does the device do SMS at all? Routers and other data-only equipment may have no SMS features. Gate openers, alarm dialers and many trackers do, usually with a fixed set of commands in the manual.
- The number format. Full international format such as +44… with no spaces works on most equipment, but check the manual: some devices want the number without the plus sign.
- Signal. A device can hold a voice or data link on weak signal and still fail to deliver SMS. See weak or no network.
- The plan. Check that your plan includes SMS and that any allowance is not used up. Ask your supplier whether the plan limits which destinations SMS can go to.
- The SMS centre number. This normally comes from the SIM. Leave it as it is unless the manual says otherwise.
Tell “not sent” from “not delivered”
- To test sending, send a message from the device to a phone you control and see whether it arrives.
- To test receiving, send a message to the SIM's number from a phone and see what the device does or reports.
- If one direction works and the other does not, the fault is in that direction: the destination format for sending, or the device's own handling for receiving.
Commands and settings
Change one thing at a time and note what happens. Use only the SMS commands in the manufacturer's manual for your exact model, and avoid unverified programming codes or resets. If a command needs a password or PIN, use the one set on the device.
What to send us
- The ICCID of the SIM and the device model
- The number you are sending to or from, and the exact text or command you sent
- What the device shows or reports, and the time you tried
Frequently asked questions
Why does my device not send or receive SMS?
The usual causes are a number in the wrong format, a device that has no SMS features, weak signal, or a plan whose SMS allowance is used up. Check them in that order.
What number format should I use?
Follow the device manual. Full international format such as +44… with no spaces works on most equipment, but some devices want the number without the plus sign.
Can I control my gate opener or alarm by SMS?
Many can, using the commands in the manufacturer's manual. Use only those commands for your exact model, and avoid unverified codes.
Still stuck? Engineer Support can continue from this guide without sending you to a generic page.