Cellular Network to IP Call

Hi there! I’m completely new to asterisk. I’d like to know if it’s possible to call someone without internet? Since SIP server needs an active internet connection, is it possible?

Support for IP is not required for Asterisk, to make calls, although some ways of making calls may require it.

Connection to the internet is not required to use Asterisk in an isolated IP telephony environment.

Support for IP is not required to call a mobile phone via an analogue or ISDN (or other circuit switched) connection to the PSTN.

Support for IP is not required to use a USB mobile network terminal.

Connection to the internet is unlikely to be required to use an IP based mobile network terminal.

Using IP without the internet may require relatively uncommon name server configurations (e.g. going authoritative for the root domain) to avoid long delays and/or failed calls.