The timeline for your number transfer is determined by your current provider and the porting providers. Here is how we communicate that date to you:
1. The Notification Email
As soon as your current provider reviews and accepts our porting request, they assign an official "Port Date." We are then provided with this information from our porting provider.
Email Confirmation: We will email you immediately once we receive this confirmed date from our porting provider.
What's in the email? We will provide the exact date for when the switch is expected to happen.
2. Typical Timelines
While every port is unique, most ports follow these standard UK lead times:
Mobile Numbers: Usually 1–2 working days after the request is accepted.
Single Landline: Usually 10–14 working days after the request is accepted.
Multi-line/Ranges: Can take 15–20 working days due to the added complexity.
🚀 What to expect on "Port Day"
On the day of the transfer, your service will move in two stages:
The "Loss of Service": Your old SIM card or landline will stop working. This is the signal that the transfer has begun.
The "Activation": Your ONSIM SIM will pick up the signal.
Note: There is often a small "transition window" (usually less than an hour) while the national routing tables update across all UK networks.
Haven't heard from us yet?
If it has been more than 5 working days since you submitted your form and you haven't received a date:
Check your Spam folder for an email from support@onsim.uk
Check for Rejections: If your port was declined due to incorrect info, we would have emailed you to request a correction.