Bulk SMS in Cambodia: TRC Rules, Sender ID and Khmer Text
Bulk SMS Cambodia guide: TRC advertising window of 08:00 to 21:00, Cellcard, Smart and Metfone routes, sender ID lead time, opt-out and Khmer Unicode length.
By OmniChannels.ai Editorial Team · Reviewed by BroadNet Messaging Solutions Team
SMS & OTP
Short answer
To send bulk SMS in Cambodia, use a provider with routes to Cellcard, Smart Axiata and Metfone, register your sender ID (typical lead time 7 to 14 business days), keep advertising SMS between 08:00 and 21:00 as the Telecommunications Regulator of Cambodia (TRC) states, separate advertising from service messages, and include a way to opt out. Khmer text is Unicode, so a single message holds 70 characters.
On this page
- What rules apply to bulk SMS in Cambodia?
- What time can you send advertising SMS in Cambodia?
- Is consent required before sending promotional SMS?
- How do sender IDs work in Cambodia?
- Which operators carry SMS in Cambodia?
- How should you separate OTP and promotional traffic?
- How does Khmer text affect SMS length?
- What is a launch checklist for Cambodia?
- A worked example: a Phnom Penh coffee chain
- What are the common mistakes?
- How OmniChannels.ai helps
Key takeaways
- The Telecommunications Regulator of Cambodia (TRC) states that advertising SMS may only be sent between 08:00 and 21:00; our regulation data records the same window and says transactional traffic runs 24/7.
- Three mobile networks appear in our coverage data, all with direct routes: Cellcard (456-01), Smart Axiata (456-04) and Metfone (456-08).
- Our regulation data lists alphanumeric sender IDs of up to 11 characters, with local script supported, set up through the operators with a typical lead time of 7 to 14 business days.
- The TRC release also requires advertising SMS to be kept separate from service-usage SMS and third-party advertisers to be clearly identified; the TRC says SMS notifications should be in Khmer or the language the customer chose at SIM registration.
- Khmer script is not in the GSM 7-bit alphabet, so Khmer messages are Unicode at 70 characters (67 per part); English-only messages in plain letters stay at 160 (153).
This guide is for marketing, e-commerce, fintech and operations teams that want to send business SMS to mobile numbers in Cambodia: OTPs, delivery alerts, reminders and promotions. It explains who regulates what, the TRC's advertising window, how sender IDs work and how Khmer text affects message length. It is a practical overview, not legal advice; confirm requirements with Cambodian counsel and the operators before launch.
What rules apply to bulk SMS in Cambodia?
Three layers apply: the TRC and operator policy, consumer and e-commerce law, and the absence of a comprehensive data protection law. There is no single "bulk SMS law", so you assemble the picture from each.
| Layer | What it covers | Where to check |
|---|---|---|
| TRC and the operators (Cellcard, Smart, Metfone) | Telecom regulation, advertising SMS window, sender ID set-up, routes | trc.gov.kh, news releases |
| E-Commerce Law | Marketing messages need clear opt-out instructions, according to DLA Piper | DLA Piper summary |
| Consumer protection rules | Unfair practices such as misleading advertising | Cambodian legislation |
Our regulation data lists the Telecommunications Regulator of Cambodia as the regulator and records that sender ID requirements are set by the operators and confirmed at onboarding.
What time can you send advertising SMS in Cambodia?
Advertising SMS may only be sent between 08:00 and 21:00. A TRC news release states that all SMS related to commercial advertising for mobile plans, services or other commercial advertisements may only be sent in that window, and our regulation data records the same limit with transactional traffic exempt at any hour.
The release adds further expectations that are sensible for any sender to follow:
- Separate advertising from service messages. Do not put offers inside OTPs or account alerts.
- Identify the sender clearly. The release requires third parties advertising through an operator network to be clearly identified.
- Follow the TRC advertising instruction. The release refers to TRC Instruction No. 9452 of 26 December 2024 on Telecommunications Service Advertising. We have not reviewed its full text, so read it or ask your provider before you write promotional copy.
The release is aimed at advertising sent over operator networks, and the exact scope for each type of sender can vary, so treat the window as the working rule for every promotion. Use the send time planner to keep campaigns inside the window, with a margin for queueing, and compare other markets in our SMS marketing rules by country.
Is consent required before sending promotional SMS?
Treat documented opt-in as required. Cambodia does not have an enacted personal data protection law: DLA Piper's guide reported in early 2026 that a draft Law on Personal Data Protection had been consulted on but not enacted, and that the E-Commerce Law allows marketing messages when each carries clear opt-out instructions and the person has not previously opted out. Our regulation data is stricter and calls for verifiable opt-in, with traffic categorised by use case at registration, STOP keyword handling and DND-registry suppression applied automatically.
We recommend following the stricter standard:
- Capture consent with a record: the exact wording, the date and time, the channel and the number.
- Say who is sending and why at sign-up, in Khmer where your customers expect it.
- Include opt-out instructions in every promotion and honour them immediately.
- Keep records per regulator requirements and keep one suppression list across channels.
- Do not buy lists.
Our opt-in consent generator drafts consent text, and the guide to opt-in consent across channels shows how to record it.
How do sender IDs work in Cambodia?
Business SMS to Cambodia uses an alphanumeric sender ID of up to 11 characters, and our regulation data notes that local script is supported. Requirements are set by the operators and confirmed at onboarding, and our data mentions that template-style approval applies in several markets. The published lead time is 7 to 14 business days. Treat it as typical, not guaranteed.
| Step | What to do |
|---|---|
| 1. Classify | Decide which traffic is transactional and which is advertising, and plan separate sender IDs |
| 2. Choose names | Use your registered brand name; avoid names that imitate banks, operators or public bodies |
| 3. Prepare documents | Business registration papers and an authorisation letter naming the sender IDs and your provider |
| 4. Submit | Your provider files with the operators; track each approval |
| 5. Test | Send an OTP and a promotion to Cellcard, Smart and Metfone handsets |
Our sender ID letter generator drafts the letter, and the sender ID checker or the Cambodia sender ID page show the current position. If you want us to prepare and file the registration with you, see registrations; approval decisions stay with the operators and regulators. For formats, read our guide to sender ID types.
Which operators carry SMS in Cambodia?
Three mobile networks appear in our coverage data, each with a direct route:
| Operator | MCC-MNC |
|---|---|
| Cellcard | 456-01 |
| Smart Axiata | 456-04 |
| Metfone | 456-08 |
Our regulation data names Cellcard and Smart Axiata for sender ID rules while the coverage data also lists Metfone; we report that difference to the content owner, and recommend testing all three. Read delivery reports per operator. Our guide to improving SMS delivery rates shows how to diagnose a weak network.
How should you separate OTP and promotional traffic?
Keep OTPs and service messages on a transactional sender ID and route, and advertising on its own. This matches the TRC's expectation that advertising is kept apart from service-usage SMS.
| Traffic | Example | Practice |
|---|---|---|
| Transactional | OTP, payment confirmation, delivery alert | No offer inside; own sender ID; any hour |
| Advertising | Sale, new product, loyalty offer | Consented numbers only; opt-out in the message; 08:00 to 21:00 |
| Mixed | "Order shipped. Get 10% off your next one" | Avoid; the offer makes it advertising |
For OTP content and security, read our OTP authentication messages guide.
How does Khmer text affect SMS length?
Khmer messages are Unicode, so one message holds 70 characters and each part of a longer message holds 67. Khmer script is outside the default GSM 7-bit alphabet, and one Khmer character switches the whole message to Unicode. English in plain Latin letters keeps 160 (153 per part). See GSM-7, UCS-2 and Unicode SMS.
| Encoding | Single message | Per part when concatenated |
|---|---|---|
| GSM 7-bit | 160 characters | 153 |
| Unicode (UCS-2) | 70 characters | 67 |
These examples were counted against the limits:
| Message | Encoding | Characters | Parts |
|---|---|---|---|
Mekong Cafe: Your code is 482913. Do not share it with anyone. |
GSM-7 | 62 | 1 |
Mekong Cafe: Buy 1 get 1 free this Saturday. Details: mekong.example/s. Stop: mekong.example/stop |
GSM-7 | 97 | 1 |
Mekong Cafe: Order #1042 arrives tomorrow before 5 pm. |
GSM-7 | 54 | 1 |
Mekong Cafe: លេខកូដរបស់អ្នកគឺ 482913។ កុំចែករំលែកជាមួយអ្នកដទៃ។ |
Unicode | 62 | 1 |
Mekong Cafe: ទិញមួយ ថែមមួយ ថ្ងៃសៅរ៍នេះ។ ព័ត៌មាន៖ mekong.example/s |
Unicode | 65 | 1 |
Khmer copy should be written or reviewed by a native speaker; the Khmer lines above are illustrative. A Khmer promotion with an opt-out line will usually run to two parts, so count before sending in the SMS character counter. For other scripts see SMS character limits and Unicode.
What is a launch checklist for Cambodia?
- Split traffic into transactional and advertising and plan one sender ID for each.
- File sender ID registration through your provider, allowing 7 to 14 business days.
- Write consent wording and store each opt-in with timestamp, source and number.
- Put opt-out wording in every promotion, and keep advertising away from OTPs.
- Have Khmer copy reviewed by a native speaker and counted as Unicode.
- Schedule advertising only between 08:00 and 21:00.
- Test on Cellcard, Smart and Metfone handsets.
- Review per-operator delivery reports after the first send.
WhatsApp can complement SMS for customers who opted in and use the app; keep SMS as the fallback for OTPs. See how to send WhatsApp marketing messages.
A worked example: a Phnom Penh coffee chain
"Mekong Cafe" (synthetic) has 20 shops and wants OTPs for its loyalty app, order alerts and a weekly promotion.
- It registers two sender IDs, one transactional and one for advertising, and tests both on all three networks.
- It collects consent in the app and at the till, storing wording, timestamp and number.
- OTPs and order alerts are sent at any hour; the OTP language follows the customer's chosen language.
- The weekly offer is queued for mid-morning, well inside 08:00 to 21:00, checked against the suppression list and sent with an opt-out line.
- Opt-outs from replies and the link feed one suppression list shared with WhatsApp and email.
What are the common mistakes?
- Sending advertising after 21:00. Queues and time zones can push a late send past the window; schedule early.
- Offers inside OTPs. It breaks the separation of advertising and service messages.
- No consent evidence. Without a timestamp and source you cannot answer a complaint.
- Assuming Khmer fits 160 characters. It is Unicode at 70.
- Treating lead times as promises. Plan buffer beyond 7 to 14 business days.
How OmniChannels.ai helps
OmniChannels.ai is powered by BroadNet, which has direct routes to Cellcard, Smart Axiata and Metfone in our coverage data. We prepare and file sender ID registration with you, support Unicode and English content, and give you per-operator delivery reports, with SMPP 3.4 for high volume. For indicative list prices, see the Cambodia SMS pricing page, then book a demo. Small team? Our SMS marketing guide for small businesses covers the basics.
Frequently asked questions
Is bulk SMS legal in Cambodia?
Yes. Businesses send OTPs, alerts and promotions through operator routes, subject to TRC rules. The TRC limits advertising SMS to 08:00 to 21:00 and expects advertising to be kept separate from service messages. Use a legitimate route, hold consent evidence and give recipients a way to opt out.
What time can I send promotional SMS in Cambodia?
The TRC states that advertising SMS may only be sent between 08:00 and 21:00 local time, and our regulation data records the same window. Transactional messages such as OTPs and delivery alerts are not advertising and can be sent at any hour. Schedule campaigns inside the window with a margin for queueing.
Does Cambodia have a data protection law?
Not yet. DLA Piper's guide reported in early 2026 that a Law on Personal Data Protection had been drafted and consulted on but not enacted. Existing rules include the E-Commerce Law, which the guide says allows marketing messages when each includes clear opt-out instructions and the person has not opted out. Take local legal advice.
Do I need to register a sender ID in Cambodia?
Plan on it. Our regulation data lists alphanumeric sender IDs of up to 11 characters, with local script supported, set up through the operators, with BroadNet confirming current requirements at onboarding and a typical lead time of 7 to 14 business days. Timing is a range, not a promise.
Do Khmer messages use GSM-7 or Unicode?
Unicode. Khmer script is not part of the GSM 7-bit alphabet, so a single message holds 70 characters and each part of a longer message holds 67. English written in plain Latin letters can still use GSM-7 at 160 and 153. Mixing one Khmer word into an English message makes the whole message Unicode.
Should OTPs be in Khmer or English?
Either works technically. The TRC says SMS notifications should be in Khmer or the language the customer selected at SIM registration, so Khmer is the safer default for consumers. A short English OTP stays at 160 characters in GSM-7, which can be useful for tourists and businesses. Offer the language the customer chose.
Sources
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