Redeem PSN card in another region?

I have a PSN account that is linked to the Switzerland region. However, I live in Germany, which means that I can't add any credit. The store is in the Switzerland region and so is the PSN profile. Is it possible to buy a card online (in my case one with Swiss francs) and then redeem it there?

For example, you could purchase keys on MMOGA, and these will then be sent to you by email.

You just have to make sure that it says Region Switzerland.