Yes, you can absolutely keep your existing landline number with the landline replacement.
At ONSIM, we specialise in "Number Porting"—the technical process of moving your current phone number from your old provider (like BT, Sky, or Virgin) onto our modern network.
This means you don't have to update your stationery, notify all your contacts, or worry about missing important calls.
How Porting Your Number Works
We handle the heavy lifting to ensure your number moves over smoothly. To get started, you just need to follow a few simple steps.
1. The Golden Rule: Don't Cancel Yet!
Important: Do not cancel your current landline contract before the porting process is complete. If you cancel your service early, your old provider may "release" the number back into the general pool, and it could be lost forever. Your number must be active to be moved.
2. What We Need From You
To start the move, please email support@onsim.uk with the following:
A Completed Porting Form: We will provide this simple document for you to sign.
Your Latest Bill: A copy of your most recent invoice from your current provider. This helps us verify that you are the legal owner of the number.
3. The Timeline
Standard Move: On average, it takes 10 to 14 working days to move a landline number in the UK.
The "Switch" Day: On the day the number actually moves, there is usually a very brief window (often just a few minutes) where the line is silent while the networks update. We will email you in advance to tell you exactly which day this will happen.
🛡️ Frequently Asked Questions
Will it affect my broadband?
If your internet comes through the same copper wire as your phone line (standard ADSL or FTTC), porting the number might automatically cancel your broadband.
Solution: Tell your current provider you want to "renumber the broadband." This keeps your internet active while letting your phone number move to ONSIM.
Can I use my number while waiting?
Yes! We will give you a temporary number to use immediately. We can even set your "Caller ID" so that when you call out, people see your real landline number even before the official move is finished.
Does it cost anything?
Your first port request is free. We do not charge for the standard transfer of your number.
Please Note: Charges will only apply if a port request is declined by your current provider due to incorrect information being supplied (such as an incorrect account number or address). This fee covers the administrative cost of resubmitting the request to the national database, so please ensure your details match your latest bill exactly.
Ready to Secure Your Number?
Our landline replacement plan is launching soon.
To join the waiting list add your email address here.