How to create a portable GSM BTS which can be used either to create a private ( and vendor free! ) GSM network or for GSM active tapping/interception/hijacking … yes, with some (relatively) cheap electronic equipment you can basically build something very similar to what the governments are using from years to perform GSM interception.
vmdialer is a simple app that lets you operate a cellular modem (pre-paid or otherwise) from Virgin Mobile or Verizon on a Linux machine. The cell modem must be activated on a Windows machine before it'll function because the PROM has to be programmed with a special app, but once that's done you can use it with this app.
Note that the exact make and model is "Novatel Wireless MC760".
FrequencyCheck is a website that helps you determine if your current cellphone will work on the cellular networks of a particular country. You can either search for devices compatible with a particular carrier, or carriers compatible with a certain mobile device.
International cellular provider that offers data only SIM cards for iot hackers. You get 1 meg a month of data. They're free to start with but you have to pay shipping. They also offer a device management dashboard for your projects. Entirely self-serve.