I've been using the Knowroaming SIM card sticker a...

I've been using the Knowroaming SIM card sticker a few times a year. It always works very well for me in Europe, but I cannot count on it elsewhere. In Bangalore, India I got no connection and customer service was not helpful. For two weeks they kept telling me to repeat the same procedure. This never fixed the issue. In Tanzania the connection was only intermittent and very slow (this was in Stone Town, not a remote area).

My husband also tried the Knowroaming sticker but it didn't work that well for him. He has a cheaper Android phone (Motorola G, 2nd gen). He has no issue getting 4G signals at home, but when he roamed in Europe with the SIM sticker he often got no signal at all (or just EDGE) while I had no trouble with my LG G4.

I sincerely hope this SIM card sticker gets better because it's such a great idea, free WhatsApp is also a very useful bonus. Just know that right now it's not totally reliable.