This guide details how to port a landline number to Onsim, if you would like to port a mobile number, please see our mobile porting guide.
To transfer your existing landline number to Onsim, we’ll need the following two documents:
1. Port form (attached at the bottom of this article). Needs to be printed on your company letter headed paper, fully completed, signed and dated.
It is imperative that the information submitted on the port forms is correct and written clearly. We strongly recommend that you request the information needed to complete the form from your existing provider to ensure the information provided is correct.
We cover the cost of the first single line number port for you, however if the port fails due to the wrong information being submitted we reserve the right to pass on the charges for any subsequent port submissions to you.
2. A copy of your latest invoice from your current provider showing the address they hold for you.
Both of these then need to be emailed to our support team (support@onsim.uk) so that we can complete our initial checks and begin the porting process.
Key Points to Remember When Porting Your Number:
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You must have an active service with Onsim before we can request the port.
We will provide you with a temporary number while the port is in progress. Once we receive your Port Authorisation Form, we will update your caller ID so that outgoing calls show the number you are porting. -
You must also keep your service active with your current provider.
If they disconnect the number before the port is complete, you could lose it and the port would not be possible.
If you would like incoming calls to reach your Onsim SIM during the porting process, please ask your current provider to forward all calls to the temporary number we’ve given you.
Porting FAQS
What is the CUIPID/Underlying Carrier?
The CUPID/Underlying Carrier is the owner of your number. For Example, Sky may be your provider but the underlying carrier is the one who owns the number in the background. This could be Sky themselves or it could be BT, TalkTalk, Gamma or another provider.
How long will it take?
The process can vary depending on your current provider. On average, porting takes around 10–14 working days after we receive your form and complete our initial checks. However, delays can occur in exceptional cases, and we cannot guarantee specific porting times due to the many factors involved.
Will I be charged for the port?
We cover the cost of the first single-line port for our customers. However, any additional ports or multi-line ports will be chargeable.
Please note that we do not cover any porting fees that may be charged by your current provider.
If a port fails due to incorrect information being provided, we will need to pass on the failed port charges to you.
Similarly, if you decide to cancel the port once the process has started, you will also be responsible for any associated charges.
You can find full details of our porting charges- Non Standard Charges
What if I have broadband on the number I would like to port?
If you have broadband on the number you wish to port over to Onsim, we will need this to be altered before we can proceed with the port.
To do this you need to email your current provider to ask them to renumber the broadband (so that the broadband is placed on another number), please ask them to ensure that the service on the number which is to be ported remains active and is NOT disconnected otherwise you would lose the service on the number you are wanting to port over.
Why do I need to pay for 2 services while the port is taking place?
You will need to pay for both your service with us and your service with your old provider while the port is taking place so it is essential that the information we receive is correct to prevent any unnecessary delays.
You need to have an active service with us as we are unable to port the number into our range without you having this and you need to have an active service with your old provider as the number has to have an active service linked to you to be able to port.
Can my old provider refuse to allow the port?
No, your old provider should not be able to prevent you from bringing your number with you. Number portability is regulated by Ofcom and if you need further information regarding this please contact us by emailing our support team (support@onsim.uk)