There are a number of internet linking standards where a repeater is connected to (generally using a computer) the internet.
Often you can use DTMF tones to control the link, or an App, a website or a combination of these. Sometimes it's programmed into the radio itself.
Networks like AllstarLink, Echolink, IRLP, System Fusion, D-Star, DMR, Brandmeister.
These don't generally interlink, but some repeater owners have developed computers (also known as nodes) that have multiple networks with the ability to interlink.
AllstarLink for example is originally based on the open source telephone exchange (PABX) software Asterisk.
Some platforms require central control and authentication, others require an account for the repeater owner.
If your radio has DTMF, you can participate in much of this all across the world. You don't need to wait for a net to get started, just instructions on how the repeater near you is configured. Often you can just ask on the repeater for help.
Related to this is a thing called a hotspot. It is like a personal repeater that connects to one or more of these networks, which you can then talk to with a handheld radio.
There are also HF links available across the world.