If you’re traveling with a group and staying in different rooms, what is the best way to be able to keep in touch with each other?

I’m traveling with family and we will be staying in 3 rooms in different parts of the ship. I know we can pick times/places to meet, but we’re not the most organized group of people. I’m curious about ideas to be able to connect with each other if we aren’t able to use cell phones. Do people still use walkie talkies? If we get Voom, does it typically work well enough to be able to text?