Dreami uses the contacts in your Zoi's phone. To add someone, have your Zoi exchange contact info with them in the game. Once they're in your Zoi's phone they show up in Contacts, and you can text and call them.
Contacts: everyone in your Zoi's phone, grouped by how they are related.
New chat lists the same people, so you can start a conversation with any of them.
A Zoi who has died doesn't answer: you get a vague "this number is no longer in service". They never text first again.
Babies, toddlers and children don't have phones, so there's no chat with them.
A Zoi in jail can't be texted or called. Your texts show "Not Delivered" with "This person is in jail right now", and go through again once they are out.
You can block someone too: tap the three dots in the chat's header, or use their card. Their texts and calls stop, plans with them are called off, and only you can lift it.
Switching to the Zoi who is writing back stops nothing: you watch their words appear in the box, and the text sends.
In the Android app, Call in the chat's header rings the other Zoi. See Voice calls.
In DMs, friends, family and partners of your Zoi can start a conversation themselves, now and then, sometimes with news they heard. See Zois text first.