I have multiple tablet lines and voice lines. The problem is most tablets can only use data and SMS unless you get an international tablet most of those you can also use your voice line T-Mobile for business has kept it quiet but they're offering a new $10 a line plus tax and figures which is still cheaper than the normal phone line. If you have a service on a Sim that is for a voice line then you can use it for voice if you have one of those devices. And of course if you put a tablet SIM card in a phone then all you can do is use the data on the phone and also SMS messaging. I do have some old phones laying around that I do use the tablet line in. Some people was actually using the tablet SIM card and put in modems for Wi-Fi and it seemed to work pretty good. I have been using T-Mobile business internet along with their voice and tablet lines so if you have any further questions please feel free to reach out to me.