Its advisable not to use clay sim cards at all than rely on them for convenience. I had a terrible time trying to get signals on my phone when I was in Malaysia. I couldn’t use the phone for 4 days out of the 5 days that I took it for and then I was emailed a bill of Rs 1500/- for my usage. Not a big amount, but the point is why would I pay for something that I couldnt use at all and it wasn’t even my fault. And their customer support was adamant on charging the 1500 bucks, which they did on my credit card. But for sure I wont be using their services anytime in the future now. Very disappointed!!