On the technology side, there are a number of ways to do this, but I won't go into that.
In principle, the VHF radio communication system is a bit like the 9‑1‑1 system. If there is an emergency, you dial 9‑1‑1. When you're at sea, it's channel 16. Without a VHF radio communication system, you can't communicate. Every place has different needs. Sometimes all you need is a repeater. On the other hand, it might be a bit of an investment.
There are different technologies and different ways to do it.