Is telephone communication possible without the Internet and a SIM card?

Question

mobile connection

Please tell me if there are any ways that allow you to talk on a mobile phone while in different countries without a SIM card and the Internet? What are the thoughts? Including illegal ways... if there are any, how could it be?

Answer 1

Of course not.
Although you can talk at the border. Stand in front of each other on opposite sides of the border and talk.

Answer 2

Well Mobile network hacking is quite an expensive thing, equipment is scarcely available and expensive. Soldering yourself must have a bright head and not ask questions on the toaster
On the topic, of course you can.

Answer 3

Vulnerability in the "extra services" software in the form of a virtual operator and a gateway.

Answer 4

Within the framework of gsm without a SIM card, the Internet and additional equipment, only 112 (well, or 911). If you need to directly from a cell phone, there is an option to build your own mini-gsm network (there were even articles on this subject on Habré), from the equipment you need a special model cell phone that will act as a base station, and a laptop where they will install the software of their mini-operator (msc , hlr). But in order to call outside, again, you need to connect your minigsm network to the PSTN. An anonymous way is to crash into someone's subscriber line (a modem will be needed in the laptop).