1. Customer is in a real job. Catalogue checkout, a Service Payment form (amount due), or a reminder for an existing order. Cold “pay now” list blasts are a policy and trust problem.
2. Official Cloud API send. Inside the care window, or an approved template in the right category (usually utility for an existing amount; marketing if you are promoting).
3. Settlement and webhooks. Review & Pay: Meta notifies paid. Razorpay Payment Links: shop payment_link.paid / payment.captured on your Razorpay keys — not WatsBerry Billing’s Razorpay. Agents can Sync payment status. Slack can ping catalogue payment received — Slack alerts.
4. Shopify is optional and separate. Shopify integration recovers website checkouts. Do not tell a UAE Shopify merchant that India WhatsApp Pay is their local rail.