The 24-hour customer service window, and Business Verification

Everything covered so far — approved templates, categories, review — applies to messages a business initiates. The moment a customer messages the business first (or replies to something the business sent), that opens a 24-hour customer service window: for the next 24 hours, the business can reply with plain, free-form text, no template or approval needed, exactly like a normal support conversation.

This is why a button tap or a free-text reply to a reminder matters beyond just "the customer responded" — it's also the mechanism that unlocks a conversational reply. A patient who taps "Cancel" on an appointment reminder and gets back a plain "Your appointment has been cancelled" isn't receiving a special new kind of message — that's a normal free-form send, made possible because the tap itself opened the window.

If a business needs to reach someone again after the window has already closed — a follow-up reminder, a "did you still want that?" nudge — that's back to template-only territory, since the customer hasn't initiated anything new. This is a real design constraint on any conversational or AI-assistant-style feature: a bot can chat freely for 24 hours after being messaged, but re-opening the conversation on its own initiative later requires an approved template, not just "send whatever the bot wants to say."

A brand-new, unverified WhatsApp Business Account starts at a modest limit on how many business-initiated conversations it can start per rolling 24 hours (Meta refers to this as a messaging limit tier). This is deliberately low to prevent abuse from day one — it's not a bug or a mistake in setup, it's the default starting point every new account begins at.

Business Verification confirms that the legal entity behind a Business Portfolio is real, using official government-issued business documents — it is a check on the company, not a KYC check on an individual, and it's a separate process from App Review (which is about specific API permissions, not the business's legal identity).

What it unlocks: verification raises the messaging limit tier substantially, and it's also a prerequisite for adding additional phone numbers to an account without running into the same low unverified-account caps. It is not required for the integration to function at all — an unverified account can send real messages today, just at a lower ceiling.

Verification review typically takes a few business days, though it can range from under a day to considerably longer if Meta requests additional documentation. Rejection isn't final — Meta generally states a reason, and resubmission after fixing the specific issue is normal, not exceptional.

Passing Business Verification does not automatically grant the green "Verified" checkmark seen on some business profiles. The checkmark is a separate, optional, discretionary badge Meta grants to businesses with public brand recognition, applied for after verification. It's a trust/visual signal for end users — messages send identically with or without it, so it's worth pursuing later as a polish item, not a blocker for anything technical.