Skip to main content

Unable to Receive SMS?

To strengthen anti-fraud and anti-spam efforts, Chinese mobile carriers have been implementing increasingly strict SMS regulations since 2015, as mandated by regulatory authorities. The following three major policies may result in SMS delivery failures, delays, or recipients not receiving messages. Please review and update your configuration accordingly:

  • SMS signatures must be real-name registered before messages can be sent.
  • Messages containing URLs or contact information are highly likely to be blocked.
  • Carriers enforce nighttime SMS rate limiting (typically between 11:00 PM and 7:00 AM).

SMS Signature Must Be Real-Name Registered​

To enable SMS sending, an organization admin must complete real-name registration of all SMS signatures.

Go to [Org Admin] > [Organization] > [Org Info] > [Verification Info], where you can manage and register SMS signatures.
Learn more about signature registration

Still Not Receiving SMS After Signature Registration?​

Submit SMS Template for Approval​

If your messages still fail to deliver despite being compliant, you can submit the SMS template for approval to reduce the risk of carrier interception.

Click here to submit your SMS template for approval

Please ensure the SMS signature is registered before submission.

Important Notes

  • Messages that contain URLs or phone numbers may still be blocked—even if approved—during ongoing regulatory enforcement.
  • For messages without links or phone numbers, after submitting the template, wait 2 business days, then perform small-batch tests to evaluate deliverability.

Possible Reasons for SMS Delivery Failure and Best Practices​

To ensure successful SMS delivery through workflows or external portals, please review the following common causes of failure and recommended practices.

Messages that include URLs, IP addresses, mobile numbers, landline numbers, or service numbers (starting with 400, 800, 9X, 12X, etc.) are at high risk of being blocked by carriers.
Unless essential, it is recommended to remove such content.

2. Nighttime Traffic Restrictions​

China Unicom and China Telecom have implemented SMS throttling during night hours (approximately 11:00 PM – 7:00 AM). Even if the message is compliant, carrier restrictions during this period may lead to delays or failures. Try resending the message during the day.

3. Incorrect SMS Type Selected​

Selecting the wrong SMS type (e.g., choosing “industry notification” for a promotional message) can result in interception:

  • Industry notification SMS must not contain marketing or promotional content and must not include phrases like “Reply R to unsubscribe”.
  • For messages such as holiday greetings, birthday promotions, or sales campaigns, always select marketing SMS.

4. Improper Message Format​

  • Total SMS length (including signature) must not exceed 500 characters.
  • All characters—including Chinese characters, letters, digits, punctuation, and spaces—count as one character each.
  • Avoid using 【】, as they conflict with signature formatting.
  • Unsupported symbols include: ￥, ★, ✓, ☞, ※, etc, or any combination characters entered via keypad (e.g., ^_^&)

5. Message Content Too Generic or Vague​

Messages like '123', 'test message', or 'notification' may be treated as spam or invalid test content and get blocked.
Even for testing purposes, use realistic, professional message content to ensure proper delivery.

6. Other Triggers​

Certain words or sentence structures may still trigger carrier review and enter manual verification, causing delivery delays or failures. Always avoid sensitive or ambiguous language to reduce risk.