SMS is not one thing. It is a family of services — each with its own delivery rules, regulatory category, timing restrictions, sender ID requirements, DLT registration path, and ideal use cases. Using the wrong type costs you money, gets your messages blocked, and can result in TRAI penalties. This guide covers every type of SMS service used in India — Promotional, Transactional, OTP, Flash, Missed Call, Unicode, Bulk, and API SMS — with the full DLT compliance rules, real me
