In this guide · 8 sections
- 01Who must check the Do Not Call Registry
- 02What counts as a marketing ('specified') message
- 03Clear and unambiguous consent: the exemption
- 04How to check numbers: account, methods and fees
- 05Build DNC checks into your CRM, email tool and WhatsApp flows
- 06Common mistakes small businesses make
- 07Do it yourself or get help?
- 08Frequently asked questions
Short answer
Before sending a marketing call, SMS or WhatsApp to a Singapore number, check it on the DNC Registry within the previous 21 days, unless the person gave clear and unambiguous consent or it relates only to an ongoing relationship. Each main account gets 1,000 free checks a year.
Who must check the Do Not Call Registry
The DNC Registry lets individuals opt out of marketing messages to their Singapore phone number. It has three registers: voice calls, text messages and faxes. According to PDPC's guide to the DNC provisions, if your organisation sends marketing messages to Singapore numbers you must check the Registry first, unless you have valid consent.
WhatsApp is covered. PDPC's Advisory Guidelines on the DNC Provisions state that the rules apply to all means of sending a message to a Singapore telephone number, including voice calls, SMS and data apps such as WhatsApp, iMessage or Viber that use a Singapore number. Email is not covered by the DNC rules, though other PDPA and spam rules apply.
What counts as a marketing ('specified') message
The PDPA calls marketing messages 'specified messages': anything that advertises, promotes or offers goods, services, property or business opportunities, or promotes the supplier. PDPC stresses that a message with any marketing element counts, even if it is mostly a service message.
| Message | DNC check needed? | Why |
|---|---|---|
| SMS announcing a weekend sale | Yes | Promotes goods |
| WhatsApp offering a new service package | Yes | Offers services |
| Appointment reminder | No | Relates only to a transaction the customer entered into |
| Delivery confirmation | No | Confirms the customer's transaction |
| Delivery update that includes a discount code | Yes | Any marketing element makes it a specified message |
| Renewal notice to an active member | No | Ongoing relationship, sole purpose is that relationship |
| Promotion to a company's office landline | No, if purely B2B | B2B messages to business numbers are excluded |
The ongoing relationship exception needs both an ongoing relationship (a membership, subscription, account or loan, not a one-off purchase) and a message whose sole purpose relates to that relationship. A customer who bought once from your online store last year is not in an ongoing relationship.
Clear and unambiguous consent: the exemption
You do not need to check the Registry if the person has given you clear and unambiguous consent to receive the messages. PDPC sets out what that means:
Consent that meets the DNC rules
PDPC's example of good wording: a checkbox stating 'I agree to receive information by SMS about special offers from [Your Company Name]'. Record the date, the wording shown and the number, so you can prove consent if asked.
How to check numbers: account, methods and fees
From PDPC's page on how to check numbers against the DNC Registry (published 22 April 2026):
Create a main account on the DNC Registry portal
Singapore organisations need their UEN and a representative with Corppass access to the DNCR e-Service. The one-time fee is S$32.70 including GST.
Add sub-accounts if needed
Staff can have sub-accounts, and credits can be moved between main and sub-accounts.
Check the numbers
Small Number Lookup for fewer than 10 numbers gives instant results. Bulk Filtering takes a CSV of 8-digit numbers, with results within 24 hours. An API gives instant results for 10 to 100 numbers.
Send within 21 days
Results are valid for 21 days from the check. After that, check again before sending.
Each main account gets 1,000 free credits a year. After that, prepaid credits cost from S$109 for 5,000 checks (about 2.2 cents a number) down to about 1.1 cents a number at 1 million, or pay-per-use at about 2.7 cents a number with a S$10 minimum. All prices include 9% GST.
Build DNC checks into your CRM, email tool and WhatsApp flows
Manual checks work for an occasional campaign. If you send regularly, build the check into the process so nobody forgets:
- Keep a consent field per contact: 'SMS/WhatsApp marketing consent: yes/no, date, wording'. Contacts with valid consent can skip the check.
- Store the DNC result and date: add 'DNC status' and 'checked on' fields in your CRM, and block marketing sends where the check is older than 21 days.
- Automate the check: the DNC Registry API lets existing account holders check numbers from their own systems before each campaign.
- Separate service and marketing templates: keep reminders and confirmations free of promotions, so they stay outside the DNC rules.
- Handle opt-outs automatically: a reply such as 'STOP' should update the contact record so no further marketing goes out.
For WhatsApp, automated messages go through the WhatsApp Business Platform with approved templates; see our WhatsApp Business API cost guide. If you also run email campaigns, our Mailchimp vs Brevo vs Klaviyo comparison covers consent and unsubscribe handling there.
Common mistakes small businesses make
- Assuming a one-off customer is an 'ongoing relationship'.
- Adding a promo code or referral offer to an order confirmation.
- Checking a list once and reusing the result months later, past the 21 days.
- Using a staff member's personal WhatsApp to blast promotions to a customer list.
- Counting a line buried in the terms and conditions as consent.
The same care applies to review requests: a plain request for an honest review is a service-style message, but bundling it with an offer can make it marketing. Our guide to automating Google review requests shows wording that stays clean. For the wider PDPA picture, see our PDPA checklist for small businesses. This page is a plain-English summary, not legal advice.
Do it yourself or get help?
A business sending one campaign a quarter can set up a DNC account, add a consent checkbox to its forms and check numbers manually. Regular WhatsApp or SMS marketing needs the consent records, check dates and opt-outs built into your systems.
Our WhatsApp Notifications package (S$590) sets up approved templates with service and marketing kept separate and opt-outs handled. The PDPA Compliance Pack (S$690) includes consent wording for your forms and a written process for DNC checks.
Frequently asked questions
Yes. PDPC's Advisory Guidelines on the DNC Provisions say the rules apply to all means of sending a specified message to a Singapore telephone number, including data applications such as WhatsApp, iMessage or Viber. A promotional WhatsApp message to a Singapore number therefore needs a DNC check unless consent or an exception applies.
Results are valid for 21 days from the date of the check, according to PDPC. If you plan to send marketing messages after that, you must check the numbers again. Organisations must also stop messages within 21 days when someone withdraws consent.
Opening a main account costs S$32.70 including GST for a Singapore organisation, and each main account receives 1,000 free credits a year. Prepaid credits then cost from S$109 for 5,000 checks, falling to about 1.1 cents a number at volume. Pay-per-use costs about 2.7 cents a number with a S$10 minimum.
No, as long as the message only relates to the customer's own transaction, such as an appointment reminder, billing notice or delivery confirmation. If you add a promotion, discount code or referral offer, PDPC treats the message as a specified message and the DNC rules apply.
The person must take a positive action, such as ticking an unticked box, that specifically agrees to marketing messages to their Singapore phone number. It must not be hidden in general terms, and you should keep a record you can refer to later. With valid consent you do not need to check the Registry.