I retired last May and completed the standard AHV forms I had received from my Gemeinde in Ittigen, noting all my activities since the age of 16 years.

(Employers in CH, UK, and Germany), marriage, birth of children, divorce, death etc. )

These were passed to my last employer's pension fund, who on behalf of the Swiss AHV, is now paying me AHV after my 20 years of Swiss contributions.
The Swiss also pay me quite a good extra child allowance as my 2 children are still studying full time here.

My details were also passed to a Swiss AHV offfice in Geneva, who passed them on to Newcastle in UK, and Berlin in BRD.

Newcastle are paying me a pension for my 16 years of work, in Francs into my Swiss Finance Post account here.

Berlin (Maybe 12 years) keep asking for details of what I did from age 16 to when I started full time work....

The system is that each EU country where you have a claim, calculates your worth as though you were still living in that country. This money is then converted to Swiss Francs and paid every month into my Swiss account.

Tip: as you can see I worked for 48 years, but if you are missing contribution years, you should contact your fund and ask to top your contributions.

A friend of mine did this in UK, and after only 2 years receiving an increased pension the extra amount she received was more than the amount she had paid in. But you can't do this after your 60th. Birthday!