All of my co-workers know, that while I'm on road, I'm using Cellular roaming and I'm available on my other mobile number, which is delivered by a Mobile roaming provider. I'm using mobile roaming service when I'm in other countries to do phone calls and transfer data. Data roaming is another very important option I use. I am a user of data roaming sim cards on my iPad, and have internet in roaming while traveling. Also, having a travel sim makes it easier for me to reduce my Mobile Roaming Charges on Cellular roaming, so I pay less.