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FAQ

Last Updated: Dec 02, 2021

This topic provides answers to some frequently asked questions (FAQ) about message delivery to regions outside mainland China.

What can I do if I do not receive the messages that have been sent to me?

To troubleshoot the issue, you can perform the following operations:

  • If your cell phone is powered on for a long time, you can restart your cell phone.

  • If your inbox is full, you can delete unnecessary messages.

  • If your cell phone has dual SIM card slots, you can swap the SIM cards.

  • If the messages are sent to the spam folder, you can configure Short Message Service (SMS) as a trusted program in the security app that is installed on your cell phone.

If the issue persists, you can insert your SIM card into another cell phone and check whether the messages are sent to the cell phone.

What message types are supported if I send messages to Vietnam?

If you register a sender ID, one-time password (OTP) messages, notification messages, and promotional messages are supported. If you do not register a sender ID, only OTP messages are supported. They are delivered to recipients over voice calls.

What are the limits on message delivery to the US, France, India, and mainland China?

If you need to send messages to the US, France, India, or mainland China, take note of the following limits:

  • You cannot use SMS to send promotional messages to the US.

  • You cannot use SMS to send promotional messages to France.

  • You cannot call the SendMessageToGlobe API operation to send messages to mainland China. If you need to send messages to mainland China by using an International SMS plan, you must call the SendMessageToGlobe and SendMessageWithTemplate operations.

  • For more information about the limits on message delivery to India, see A2P SMS Messaging Regulations for India.

How many characters can be contained in a message?

A message can contain up to 1,500 characters.

What are the rules of setting a daily messaging frequency?

When you set a daily messaging frequency, the following rules apply:

  • To ensure user experience, the number of messages that can be sent to a mobile phone number within one day cannot exceed a specified threshold. The default threshold is 20 messages per day.

  • You can customize a threshold but it cannot exceed 20 messages per day.

  • Timing starts when the specified threshold takes effect. For example, if you send a text message at 11:00 on August 23, 2017, SMS checks whether the number of messages that are sent from 11:00 on August 23 to 11:00 on August 24 has reached the threshold. If the number has reached the threshold, you cannot send messages anymore.

Why does ".0" appear after the verification code in an OTP message?

This is because the data type of a JSON object is not a string.

Can I send a text message to multiple mobile phone numbers at a time?

No, you can select only one mobile phone number to which you send a text message at a time.

What is SMS message flooding? How can I prevent it?

SMS message flooding refers to sending a large number of text messages to a group of mobile phone numbers in a short period of time by using malicious programs. SMS message flooding may cause harassment to cell phone users who receive the text messages. SMS message flooding may also harm your brand and business. We recommend that you use the following methods to prevent SMS message flooding:

  • Enable CAPTCHAs to prevent malicious programs from using your page to send messages. Before you receive a verification code, enter the CAPTCHA that appears.

  • Set the validity period for receiving a verification code. In most cases, each verification code is valid for 60 seconds.

  • Set the validity period for entering a verification code. In most cases, each verification code is valid for 30 seconds. If you do not enter the verification code within 30 seconds, the verification code expires and you must request another verification code.

What are the possible causes for message delivery failures?

Message delivery failures may occur due to the following causes:

  • Portability Failure: In most cases, messages can be received by a mobile phone number even if the carrier is changed. However, if the new carrier does not update network routing information in time, or if the mobile phone number is transferred to a new network only within 24 hours, messages may fail to be received.

  • Handset Cannot Receive SMS: A cell phone cannot receive messages as expected in the following scenarios: 1. The memory of the cell phone is full. 2. The cell phone is in the flight mode. 3. The cell phone is out of service.

  • Sending the Wrong Content: The message content is invalid. For example, a cell phone may fail to receive the messages that are written in unsupported languages.

  • Roaming: Message delivery failures may occur during global roaming. Whether a cell phone can receive messages depends on the roaming interconnection agreement among global carriers.

  • Carrier Spam Filters: Messages are filtered by carriers because the messages include forbidden information.

How do I check whether a mobile phone number is valid?

To check whether a mobile phone number is valid, perform the following operations:

  • You can check the mobile phone number based on the international dialing rules. However, whether the mobile phone number exists, whether it is disabled, and whether its mobile network carrier is being changed cannot be determined.

If the specified mobile phone number meets the rules, messages are sent. In this case, carriers charge you even if the mobile phone number does not exist and messages fail to be received.

Alibaba Cloud SMS can retrieve detailed information by updating the carrier route databases. In most cases, you are charged for this service.