SMS sender ID prefixes in India, explained

Header, prefix or suffix?

The term sender ID prefix is left over from an older era of Indian SMS. Today the part that matters is the header: the 6-character name, such as MYSHOP, that shows in place of a phone number. What used to be discussed as a prefix is now handled by registration and a category suffix.

So three words, kept straight:

• Header: the 6-character brand name itself.
• Suffix: the category tag added to it (-P, -S, -T or -G).
• Prefix: the older numeric or operator-led style that A2P SMS no longer uses.

How headers are formed today

Under the DLT framework, every commercial header is a 6-character alphabetic name, registered to your business (Principal Entity) on the DLT portal and tied to a category. Once approved, that header is the identity every recipient sees, the same across Jio, Airtel, Vi and BSNL.

The category suffix (-P / -S / -T / -G)

From 6 May 2025, TRAI requires the message category to be visible on the header as a suffix:

The suffix makes each message traceable to its category, and a header can only send templates that match its category.

What happened to the old numeric prefixes?

Years ago, promotional SMS in India was associated with numeric, operator and circle led prefixes. The move to DLT replaced that model: identity now comes from a registered alphabetic header plus a category suffix, not a numeric prefix. If you are searching for how to get a numeric prefix for A2P SMS, the modern answer is to register a 6-character header on DLT instead.

Ready to set one up? See how to choose a sender ID and the DLT registration guide. Long messages and regional languages also change how many characters you get per SMS, covered in our SMS character limits guide.