Callback Registration & Buying 18 Years NICs from Abroad after 5 April Deadline

I understand people have 31 days to make payment following a call from DWP if they have registered on the callback facility by 5 April. If they are abroad, have registered for a DWP callback and submit a CF83 AFTER 5 April.... Will they be able to buy 18 past years? What's the cut-off point for the receipt of their fresh CF83 application if they have not submitted it by 5 April? 31 days for payment from call date makes sense for people in UK. Nowhere is the situation made clear for people abroad given DWP's commitment that once registered in time, ANYONE will still be able to buy 18 past years .... (regardless of whether or not CF83 has been submitted?) Can you urgently clarify the above with some specific details please? Many thanks

Hi,
Our customers who are contacted by DWP after the deadline can submit a CF83.
Once processed you’ll receive a letter (INSL33a) from out caseworkers detailing which years you can make payment for, at which rates and by which time. Please add "after receiving advice from DWP" in the Additional notes box on the online form.
If you are completing a print and post version of the form, please add a note to confirm that you have been advised by DWP that it is beneficial to pay. You will need to submit this as soon as possible.
You’ll be able to make payments as far back as 2006-07 provided we receive your payment before the deadline you are given in your letter. 
If you have a Government Gateway Account, you are advised to completed and submit your CF83 before the 5 April 2025 deadline.
If you receive your INSL33a and are unable to contact DWP to confirm if it is beneficial to make voluntary contributions, please complete and submit the call back request before April 5 2025.
Once you have spoken to DWP you can contact us to discuss making a payment and receive an extension if eligible. 
Thank you.
 

Helpful - thank you.