Bulk Messaging Setup & Guidance

I have a database of roughly 100,000 users with mobile number and I need a reliable, cost-efficient way to blast promotional offers to them. I’m open to several channels—DLT-approved SMS in India, non-DLT routes if there is a compliant workaround, RCS, or even the WhatsApp Business API—whichever gives the best mix of reach, deliverability, and pricing. Here’s what I expect from you: • A clear, step-by-step roadmap for registering my brand, headers, and templates on India’s DLT platforms (any operator is fine as long as the flow is explained). • Alternative options if I decide to bypass DLT—legal grey areas I should know about, reputable bulk gateways, expected costs, and deliverability stats. • An RCS or rich-media panel recommendation (setup + walkthrough) that lets me push interactive messages at scale. • Guidance on securing a low-cost WhatsApp Business API provider and the exact steps to get my number verified and templates approved. • Final comparison matrix covering pricing per message, delivery success rate, sender-ID display, and any regulatory pros/cons for each channel. Everything must respect the fact that my users have already consented to receive promotional content, so compliance and template wording tips are important. I’ll judge the deliverable on clarity, real-world vendor contacts or panels I can actually sign up with, and a short test campaign you help me run to confirm throughput.