How it works
Your server calls the gateway's API with a phone number and a message; the gateway routes it to the mobile operators and reports delivery back through a webhook or a status API. Messages are charged per segment: 160 plain characters, or 70 when the text uses emoji or Indian scripts. Twilio, Vonage, Plivo and Infobip work worldwide; MSG91, Gupshup and similar providers focus on India, often with ready-made OTP widgets.
India adds DLT (distributed ledger technology) registration under TRAI rules. A business registers as a principal entity on an operator's DLT portal (Jio, Airtel, Vi or BSNL), then registers its sender IDs (six-character headers) and every message template, with placeholders for the parts that change. Messages that do not match an approved template are blocked, links must be whitelisted, and since 2025 headers carry a suffix such as -S or -T that shows the message type.
The first portal charges a registration fee of about ₹5,000 plus GST. International routes skip DLT but deliver from random numbers. Prices vary widely: Twilio lists about $0.083 a message to India, while Indian providers charge a fraction of a rupee. Some apps send login codes over WhatsApp first and fall back to SMS.
SMS gateways pros and cons
Pros
- Reaches any mobile phone, with no app or data connection needed
- Familiar to users for login codes and alerts
- Simple API with delivery reports
Cons
- Every message costs money, unlike push or email
- India requires DLT registration of the business, headers and templates
- SMS codes can be stolen through SIM swaps or phishing
- Delivery speed varies by operator and route
When to use SMS gateways
Pick it when
- Login codes and alerts for people who may not have your app
- Critical messages that must reach basic phones
Skip it when
- Marketing blasts, where cost and spam rules add up
- The user already has your app and a push notification would do
SMS gateways pricing
Pay as you go
In India, providers such as MSG91 charge about ₹0.16 to ₹0.25 per SMS plus GST, falling with volume; Twilio lists about $0.083 per SMS to India. DLT registration is a separate fee.
SMS gateways pricing page (opens in a new tab)Approximate, checked September 2026.What the other tools cost
SMS gateways vs the alternatives
Related terms
More in Email and notifications
SMS and chat