ChatSim is a data-only SIM card that works with roaming partners in well over 100 countries and allows you to send and receive unlimited text and emoji. Your phone number is based in Estonia — anywhere else, and you’re connecting to a local network as if you were roaming. In this case, roaming doesn’t mean anything for you — you’re still paying the flat €10 that gets you the SIM card in the first place. Because text and emoji sent and received through messenger apps use such a small amount of data, ChatSim can work with its roaming partners to make that traffic unlimited for you.
Here’s where things get complicated. ChatSim is a data SIM card, but there’s no way for them to only authorize data use only for chat programs on their end. It’s still possible for you to browse the internet, download apps, watch movies, or do anything else data-intensive using ChatSim. While they can’t block that traffic, they can detect when you’re using ChatSim for uses other than chat by looking at data transfer rates. If they detect abnormal usage, they will lock your SIM card, and you’ll need to sign into your account and ask ChatSim to unlock it.
The tricky part is configuring your phone to not get your SIM card locked. You’ll need to deactivate app updates over data networks, disable background data for any app that isn’t a messenger app, and stay away from your web browser while you’re using ChatSim. The harder part is making sure all of your contacts know (and remember) to not send you pictures or video — while some chat apps let you disable receiving images and video, others don’t. While it’s easy to slip up and get your ChatSim locked for abnormal usage, it’s also easy to get your card unlocked — it’s a matter of clicking a button on the ChatSim website. However, you can only unlock your card that easily five times before ChatSim gets more serious about data infractions.