If you hear this recording when trying to place a call, it is usually caused by one of two things: incorrect number formatting or an out-of-plan destination.
1. Check Your Number Formatting
If the number is stored incorrectly in your contacts, your handset may be adding extra digits that make the system think you are dialing a restricted international or premium number.
The +44 Rule: Ensure your contacts are saved in the format +447... instead of 07... or +4407...
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Disable "Dial Assist": This smartphone feature often automatically adds prefixes that conflict with VoIP systems.
iPhone: Settings > Apps > Phone > Toggle Dial Assist to OFF.
Android: Phone App > Settings > Assisted Dialing > Toggle OFF.
See our [Number Formatting Guide] for a full walkthrough.
2. Inclusive vs. Non-Inclusive Numbers
By default, ONSIM plans are restricted to the most common UK destinations to protect you from high "out-of-bundle" costs.
What is included by default:
Standard Landlines: Starting with 01, 02, or 03.
Major Mobile Networks: O2, Vodafone, EE, and Three (starting 07).
Freephone: 0800 and 0808.
What is restricted by default:
Non-Standard Mobiles: Certain 07 numbers used by smaller virtual networks.
Service Numbers: 0845, 0870, 09, etc.
International Destinations: All calls outside of the UK.
3. How to Enable Restricted Calling
If you need to reach a number that is currently blocked:
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Special UK Numbers: To enable calls to numbers like 0845, email support@onsim.uk.
Note: These calls will incur additional per-minute charges that are not covered by your inclusive allowance.
International Calling: To lift international restrictions, please refer to our International calling guide.