SMS Delivery Testing Before Launch: The Practical Pre-Production Checklist

In India's DLT-regulated SMS environment, silent failures often come from template mismatch, wrong pe_id / template_id, or untested operator paths - not from a missing semicolon. Use this checklist alongside the SMS API reference and integration guide.

1. Test numbers and account setup

• Credentials in env vars: use separate non-production credentials when SMSTAKE has issued them during onboarding. Confirm with the team what test or low-risk routes are available for your account - do not assume a public sandbox exists for every plan.
• Internal test roster: keep handsets on Jio, Airtel, Vi and BSNL that your team owns, so you can check real inbox receipt.
• Store ack_id: every successful submit should persist the acknowledgement id for DLR matching.

2. Operator and device coverage

• Multi-operator sends: fire the same approved template to each major operator and compare submit latency and final DLR.
• Weak coverage: for OTP flows, verify your retry / Voice OTP fallback when SMS is slow or fails - see Voice OTP as SMS fallback.
• Header rendering: confirm the approved sender ID appears as expected on Android and iOS default SMS apps for a few sample devices.

3. DLT template matching and variables

Under TRAI rules, small text differences cause rejection. Details: DLT guide, variable tagging, why SMS delivery fails.

• Exact string match: fixed text in the API text field matches the approved template character-for-character (spaces and punctuation included).
• Typed variables: use portal tags such as {#numeric#} and {#alphanumeric#} - not the old generic {#var#}. Values must fit the tag rules.
• Correct IDs: pass from (header), pe_id and template_id as documented - not invented names like peid / tempid.
• URLs and PE-TM chain: whitelist links before use; confirm SMSTAKE is on your PE-TM chain.

4. Delivery reports and webhooks

• Webhook endpoint: HTTPS URL reachable from the internet; verify signature when enabled; return 200 OK quickly. Patterns: DLR webhook integration guide.
• Pull fallback: exercise dlrresp.jsp with a known ack_id if you also poll.
• Status handling: exercise logic for submitted / in-progress vs final outcomes such as delivered, failed, rejected, expired or undelivered (exact labels depend on your DLR mapping - see delivery reports explained). Never let a late "submitted" overwrite a final status.
• API error codes: confirm your client handles SMSTAKE submit errors such as 010, 103, 104 and 105 from the SMS API docs.

5. Controlled rollout

• Canary: send live traffic to a small slice of users (for example 5-10%) or a single product surface first.
• Watch the first hour: submit error rate, time-to-first-DLR, and share of failed/rejected vs delivered.
• Scale when stable: increase volume only after canary metrics look healthy for your use case - do not treat a generic "99%+" figure as a guarantee.
• Rollback plan: know how to pause the new template or route and revert to the previous path.

SMS API docs · Postman collections · Bulk SMS