TRAI’s February 2025 amendment added rules on inactive headers and on how templates are built. Both can cause failures that look puzzling at first.
Headers unused for 90 days are deactivated #
If a header (sender ID) sends no messages for 90 days, it is deactivated automatically. Messages sent with it afterwards fail as an invalid or blocked sender.
- To reactivate: log in to your DLT portal and request reactivation of the header.
- To prevent it: review your headers every quarter. Retire the ones you no longer need and keep the rest in use.
Limits on template variables #
- A template can normally have up to three variables. More are allowed only in special cases, with justification to the operator.
- At least 30% of the template must be fixed text. A template made almost entirely of variables will be rejected.
- Each variable must use the correct tag, such as
{#numeric#}or{#url#}. See What are DLT variable tags, and which one should I use?
One template, one header #
A content template cannot be linked to more than one header. If you send the same text from two headers, register it once per header. Otherwise the message fails with a sender ID mismatch (SENDERID_MISMATCH).
Quick checklist before registering a template #
- The right category (see Which category should I register my DLT template under?)
- Mostly fixed text, with no more variables than you need
- Every link and callback number whitelisted
- Linked to the single header that will send it
Official source: TCCCPR (Second Amendment) Regulations, 12 Feb 2025.
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