My previous experiences of using international sim cards wasn’t great, so when I was traveling to Shanghai last month, I was adamant on using my indian number only and nothing otherwise. Since it was a work trip, and I was given a matrix sim card for my usage there, I carried it along still wanting to use my indian number. Surprisingly it was my indian number that gave me trouble there until I started using the matrix sim card. It was smooth, it was more convenient and it was faster than what I had expected. I had absolutely no issues while I was making or receiving calls. Quite unlike other international services that I had used in the past. Thanks guys, for this experience.