[hrgajek]

After more testing, the Kwowroaming Sticker told me "invalid SIM" and so I fiddled it out of my DUAL-SIM Androide and checked it with another Mobile Phone (good old original Nokia) same error. So I had to peel of the Sticker, the original SIM (Simyo) works fine.

I've informed KnowRoaming about my experiences. I'll keep you informed.

N.B. From the technological aspect, the idea of the sticker is
smart, but you have to be very careful not to damage the SIM-card Slot of your phone.

If this kind of SIM-card is useful or necessary for Europeans with european tariff-regime is another story - it still could be interesting for roaming around the world or far away at Russia, China, Americas (North/South), Australia etc. if you do not want to buy a local SIM card. But thats is another story.