OFFICIAL · Singapore regulatory framework

IMDA in practice: CLI verification, the SMS Sender ID Registry (SSIR) and the Likely-Scam policy for A2P traffic into Singapore

Whereas, in exercise of the powers conferred by the Telecommunications Act, the Infocomm Media Development Authority (IMDA) administers the +65 numbering plan and the SMS Sender ID Registry (SSIR). Four mobile operators cover the island: Singtel, M1, StarHub and SIMBA (formerly TPG). 4notify routes via direct tier-1 interconnect with all four, registers Alphanumeric Sender IDs through the SSIR and enforces the Likely-Scam policy at the API edge. Traceable delivery, no grey-route, no Likely-Scam label against your brand.

The four Singapore mobile operators

Singtel

Share: ~50% · P50: 2.4 s

Largest national operator and historical incumbent; preferred tier-1 interconnect for regulated sectors.

M1

Share: ~16% · P50: 2.7 s

Keppel Telecom-affiliated operator with strong enterprise A2P coverage and consistent Alphanumeric Sender ID acceptance.

StarHub

Share: ~21% · P50: 2.8 s

Second-largest operator; urban depth, broad MVNO host for sub-brands; reliable SSIR routing.

SIMBA (TPG)

Share: ~13% · P50: 3.0 s

Fourth operator (formerly TPG Telecom Singapore); price-led growth and full SSIR participation.

IMDA numbering plan

+65 8xxx / 9xxx — MobileAllocated to the four MNOs and authorised MVNOs; mandatory CLI integrity chain.
+65 6xxx — Fixed and IP voiceGeographic and VoIP enterprise lines.
Short codes (4-5 digits)Two-way SMS; brand registration with the operator; dedicated or shared.
Alphanumeric Sender ID (≤11 chars)Registered through the IMDA SSIR; non-registered IDs default to 'Likely-Scam'.

The five-step IMDA SSIR compliance chain

  1. 01

    IMDA SSIR registration plus operator contracts

    4notify is registered through the SSIR as a participating aggregator and holds Sender ID agreements with Singtel, M1, StarHub and SIMBA.

  2. 02

    Alphanumeric Sender ID enrolment

    Brands register their Sender ID through the SSIR portal. Requirements: ACRA-registered entity or recognised trademark, sample message, declaration of use. Activation in 5-10 working days.

  3. 03

    Likely-Scam policy enforcement

    Any unregistered alphanumeric ID is rewritten as 'Likely-Scam' by all four operators. 4notify rejects unregistered Sender IDs at the API edge — the label never appears against your brand.

  4. 04

    Lawful-basis enforcement under the PDPA

    For commercial messages the PDPA lawful basis is checked at the envelope layer; deliveries without permission are blocked at the API edge before they reach an operator.

  5. 05

    STOP keyword and DNC processing

    For every commercial message, STOP and UNSUBSCRIBE replies are processed within 3 days and reflected in the suppression list, in line with PDPA and DNC obligations.

Frequently asked questions

Do I need a Singapore-incorporated entity to send SMS into Singapore?

4notify operates the tier-1 interconnect from European infrastructure, but for SSIR Sender ID registration IMDA expects an ACRA-registered entity or a recognised trademark holder. We accompany the application through Singtel, M1, StarHub and SIMBA.

What is the sanction for spoofing a reserved Sender ID?

Spoofing a registered Sender ID may trigger IMDA enforcement, criminal liability under the Computer Misuse Act and civil exposure under the PDPA. The SSIR Likely-Scam label is the structural defence: any unregistered alphanumeric ID is automatically downgraded by the network.

How long does Alphanumeric Sender ID activation take?

Typically 5-10 working days through the SSIR portal. Singtel is often fastest; M1, StarHub and SIMBA can take 1-2 working days more.

Start free

Full IMDA SSIR compliance. Sender ID activation in 5-10 working days. English support on weekdays.