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💬 Troubleshooting: SMS Not Sending or Receiving

ONSIM
Updated

SMS issues are often separate from data or voice problems. If you are struggling to send or receive texts—especially Two-Factor Authentication (2FA) codes—follow this diagnostic guide.

1. The "Number Type" Rule (Crucial)

The most common reason for not receiving an SMS is trying to send it to the wrong type of number.

  • Mobile Numbers (07xxx): These are fully SMS-enabled. They can send and receive texts globally.

  • Landline Numbers (01, 02, 03, 08): Landline numbers are Voice Only. They cannot receive SMS or 2FA codes.

  • The Fix: If a service (like a bank or social media app) asks for a number to send a security code, always use your 07 mobile number, even if your landline is your primary business contact.

2. Troubleshooting 2FA & "Short code" Texts

If you aren't receiving automated codes from banks or apps (known as "Short codes"):

  • Carrier Lookup: Some apps "remember" your old network. If you recently ported your number to ONSIM, it can take up to 72 hours for global SMS routing tables to update.

  • Device Settings: 

    • iPhone: Go to Settings > Messages > Send & Receive and ensure your 07 number is ticked.

    • Android: Open the Messages app, go to Settings, and ensure your "Message Center Number" is correctly configured (Contact support if you need this number).

3. Basic Connectivity Fixes

Before escalating, try these "quick clears":

  • Toggle Airplane Mode: Turn it on for 10 seconds and off again to refresh the network "handshake."

  • Check Storage: If your phone's internal storage is completely full, it may stop accepting new SMS messages.

  • Delete Old Threads: Very long SMS threads with thousands of messages can sometimes cause the messaging app to hang.

4. How to Report a Persistent Issue

If the basics haven't worked, our engineering team needs to trace the specific "path" of the failed message. To investigate, we require 3 specific examples from within the last 48 hours.

Please provide:

  1. The Sender's Number (or the name of the service, e.g., "HSBC").

  2. The Recipient's Number (Your 07 ONSIM number).

  3. The Exact Time and Date the message was sent.

💡 Tip:  Ready to report? Use our portal to submit these details directly to the technical team: Click here for our guide on creating a support ticket via the online portal.

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