Filling NI gaps with 'credits' from working abroad

I understand that I can use social security contributions from working in USA to fill gaps in my UK contributions? I have a 10 year gap and worked in USA for 4 years and EU for 3 years during this time. How can I do this please?

Hi N Goodall,
When you claim your UK State Pension with The Pension Service you would include details of your employment in other countries and they may be able to include these periods when they calculate your pension.
You may wish to call the International Pension Centre on 0191 2187777 and they will be able to help you further.
Thank you. 

Thank you. I did phone the International Pension Centre and they told me to call the Future Pension Centre. They were also unable to tell me. I need to decide before April whether to purchase 2 years (06/07 & 07/08) Class 3 or whether I am eligible to purchase Class 2 due to being abroad under vague rules stated on Gov.uk website pr whether I need to pay anything at all? I obviously don't want to wait until retirement until retirement to deal with this. It's been suggested that completing CF83 with a long cover letter might be the best way forward. Do you have any other suggestions?

Hi,
If you would like to pay voluntary National Insurance contributions while overseas, please read our leaflet NI38 ‘Social Security Abroad’ which you will find via:  
Social Security abroad: NI38
If you then decide to pay the voluntary contributions then please complete and submit the CF83 application form which you’ll find via:
Apply to pay voluntary National Insurance contributions when abroad (CF83)
Please include details of your employment on the CF83 application form and our International Teams will be able to assess your entitlement to pay either voluntary class 2 or voluntary class 3 contributions.
Thank you.