Have to recently notices SMS headers like Loan-P or Bank-S on your phone? That’s part of a new system rolled out nationwide from May 6, aimed at helping mobile users quickly identify the nature of every text they receive. The Telecom Regulatory Authority of India (TRAI) has introduced a suffix-based classification for all SMS messages, marking each with a letter that reveals whether it’s promotional, service-related, transactional, or government-authorized. The move, based on TRAI’s 2nd Amendment issued on February 12, 2025, seeks to improve transparency in telecom communication and reduce spam for over a billion mobile users across the country.

How the new SMS suffix system works

Under the revised guidelines, each SMS header now ends with one of the following characters:

P – Promotional messages, including service-specific promotions

S – Service messages for general customer engagement

T – Transactional messages such as OTPs or banking alerts

G – Government-authorized messages (only TRAI-exempt headers)

For example, if a service message is sent from the header "ABCXYZ" via Jio in Delhi, users will see it as JD-ABCXYZ-S.
J represents Jio, D means Delhi and the 'S' at the represent service. This clearly tells the recipient the nature of the message before opening it.

Why TRAI introduced the change

More than 1.1 billion mobile users in India regularly face spam and unsolicited SMS messages. Many users struggle to tell which messages are important and which are irrelevant. The new suffix system is designed to act as a filter to help users make faster decisions.

TRAI believes the change will also benefit businesses. With clearer headers, users may be more likely to open trusted messages, potentially increasing engagement rates. The move may also influence global telecom regulators to adopt similar reforms.

Who needs to act under the new rule

The change affects only Telecom Service Providers (TSPs), who are responsible for implementing the new suffix format. Businesses and telemarketers, known as Principal Entities (PEs), do not need to alter their existing message formats. The DLT platform, which already checks messages to prevent spam, will automatically add the appropriate suffix during processing.

TSPs were given until May 6 to complete the required updates to their systems.

What comes next for SMS in India

TRAI’s suffix rule aims to rebuild public confidence in SMS communication, which has declined due to fraudulent schemes and excessive marketing. Analysts will monitor how effective the suffix system is in cutting down spam and improving user experience. Future developments could include real-time opt-out tools, AI-based spam filters, or message verification systems across platforms.