When a customer messages you first, a 48-hour window opens in which you can reply to them free of cost. Understanding this window is important for planning your messaging flows.
The window opens the moment a customer sends you a message.
While it is open, you can send and receive whatever you need, in whatever format, handled by your live agents or your bots.
The window refreshes every time the customer messages you.
Once the 48-hour window closes, you must use an approved template to initiate messaging again. If the customer responds to that template, a new 48-hour window begins.
Conversational replies inside the 48-hour window are free. Template messages outside it are charged.
Whether customers can type back is set per number, using Allow text replies.
→ How to Set Up Your Number Profile
Even with text replies turned off, quick reply and other message buttons keep working. This means you can run a full conversation where every customer response is a button you defined.
Example: A delivery notification offers "Track order" and "Report a problem". Tapping "Report a problem" sends a message your system already recognises, and you answer with the next set of options.
More detail on message buttons and the conversational message API is available in Arattai's API documentation.