Every SMS gateway website promises "99% delivery" and "lowest prices". The differences only show up after you have signed up: OTPs that arrive in 40 seconds instead of 4, delivery reports that never update, and support tickets that go unanswered during a festival campaign. This guide covers the seven factors that separate a dependable SMS gateway from a cheap reseller, with the India-specific checks — DLT, operator routing, per-SMS pricing — that generic advice skips.
1. Delivery Rate and Routing Quality
Delivery is the product. Everything else is packaging.
- Ask how the provider connects to operators. Gateways with direct or near-direct connectivity to Airtel, Jio, Vi and BSNL deliver faster and more reliably than resellers who route through several intermediaries, where each hop adds latency and failure points.
- Expect 90 to 98 percent delivery on a clean list. No provider can honestly promise 100 percent — switched-off phones, ported numbers and inactive SIMs exist on every list.
- Test before you commit. Send a few hundred messages across operators and telecom circles (metro and non-metro) and compare delivery reports against actual handsets. A provider confident in its routes will happily give you trial credits.
2. Speed and Throughput
For OTP traffic, latency is the whole game: users abandon signups when a code takes longer than about 15 seconds, so look for a provider whose OTP route consistently delivers in under 5 to 10 seconds. For campaign traffic, ask about throughput — how many messages per second your account can submit. A 1,00,000-message campaign at 50 messages per second finishes in about 33 minutes; at 5 per second it drags on for over five hours and misses your intended send window.
3. Proper DLT Support
Since TRAI mandated the DLT framework, this is where Indian SMS projects most often stall. A good gateway will:
- Guide you through Principal Entity registration on an operator portal (Airtel, Jio TrustID, Vi or BSNL) rather than leaving you to decode the process alone.
- Let you attach your registered header (sender ID) and content template IDs to the account, and sync new templates quickly.
- Validate messages against registered templates before submission, so mismatches are caught in your dashboard instead of silently failing at the operator.
- Clearly separate promotional, transactional and service routes, including the 9 AM to 9 PM promotional window and DND scrubbing.
4. API and Platform Quality
If SMS is going into your software — OTP login, order updates, alerts — the API is your daily interface with the provider. Check for:
- A clean HTTP/REST API with JSON responses and documented error codes, plus SMPP if you need very high sustained throughput.
- Real documentation with working examples, not a single sample URL.
- Delivery report webhooks (DLR callbacks) pushed to your server, so you are not polling for status.
- A usable web panel for the marketing team: contact management, campaign scheduling, sender ID selection and exportable reports.
5. Transparent Pricing
Indian bulk SMS pricing is volume-based. As a sanity check, typical market rates look like this:
| Route | Typical price per SMS | Notes |
|---|---|---|
| Promotional | ₹0.10 – ₹0.20 | 9 AM–9 PM only, non-DND numbers |
| Transactional / Service | ₹0.15 – ₹0.25 | 24x7, reaches DND numbers |
| OTP | ₹0.15 – ₹0.25 | Priority routing, lowest latency |
Prices far below this band usually mean grey routes or heavy queuing. Beyond the headline rate, confirm three things: whether unused credits expire (and after how long), whether you are billed on submitted or delivered messages, and whether multi-part messages are billed per part (they should be — a 300-character English message is two credits everywhere). Compare current volume slabs on our bulk SMS pricing page to benchmark any quote you receive.
6. Reporting and Delivery Receipts
You cannot manage what you cannot see. Insist on message-level delivery reports with operator status codes (delivered, failed, DND, absent subscriber, expired), timestamps for submission and handset delivery, campaign-level summaries, and CSV/Excel export. Real-time DLRs matter especially for OTP flows, where you may want to trigger a voice or WhatsApp fallback when an SMS fails.
7. Support and Reliability
- Uptime: look for a stated 99.5 percent or better, and ask what happens during operator outages — good providers reroute traffic automatically.
- Human support: a phone number and a named contact beat a ticket-only system when a Diwali campaign is stuck at 6 PM.
- Escalation for DLT issues: template rejections and header blocks need someone who can talk to the operators on your behalf.
Red Flags to Walk Away From
- Promises of "100% delivery guaranteed" or promotional SMS to DND numbers — both are impossible legally.
- No mention of DLT anywhere on the website or during onboarding.
- Prices dramatically below the market band with pressure to buy large credit packs upfront.
- No trial account, no test credits, and no way to verify delivery before payment.
- Delivery "reports" that show only submitted counts, never operator confirmations.
A 30-Minute Evaluation Checklist
- Request trial credits and API access.
- Send 200 to 500 test messages spread across Airtel, Jio, Vi and BSNL numbers in at least two telecom circles.
- Measure delivery percentage and average latency against real handsets, not just the dashboard.
- Trigger a deliberate failure (wrong template variable) and see how clearly the error is reported.
- Call support with a technical question and time the response.
Run that test with two or three shortlisted providers and the decision usually makes itself.
Frequently Asked Questions
What is a good delivery rate for bulk SMS in India?
On a clean, recently active list, expect 90 to 98 percent. Rates below 85 percent usually indicate stale numbers on your list, DLT template mismatches, or a provider using poor-quality routes. No legitimate provider can deliver 100 percent, because some handsets are always switched off or out of coverage.
Do I need DLT registration before choosing an SMS gateway?
You can choose the gateway first — a good one will help you complete DLT registration as part of onboarding. But no commercial SMS can be delivered in India until your Principal Entity, header and content templates are approved on an operator DLT portal, so start the registration as early as possible; approvals typically take two to five working days.
Should I use an HTTP API or SMPP?
HTTP/REST is the right choice for almost everyone: it is simple to integrate, works from any language, and easily handles OTPs and campaigns up to tens of messages per second. SMPP is a persistent binary protocol worth the extra complexity only for very high sustained volumes, typically aggregators and enterprises pushing hundreds of messages per second.