This topic describes how message length is calculated and the rate limits for Short Message Service.
Rules for calculating message length
Message length (in characters) = Number of characters in the SMS signature + Number of characters in the SMS template. The message content cannot exceed 500 characters.
The character count of an SMS signature includes the
【】or[]symbols that the system automatically adds when sending a message.The character count of the SMS template is based on the actual content of the received message.
Message type | Length calculation rules | |
Domestic SMS | Simplified Chinese characters, letters, numbers, and punctuation marks are all counted as one character, regardless of whether they are full-width or half-width. If a message is 70 characters or less, it is billed as one message. If it is longer than 70 characters, it is a long message and is split and billed as multiple messages based on 67 characters per message. Example: A message with 160 characters is split into three messages of 67, 67, and 26 characters, and is billed as three messages. | |
International / Hong Kong, Macau, and Taiwan SMS | Pure English messages (GSM-7 encoding) | Standard characters such as letters and numbers are counted as one character. Extended characters are counted as two characters. Extended characters include the following: If a message contains other unlisted extended characters, the entire message is calculated based on the rules for other languages (UCS-2 encoding), regardless of its length or whether it is split. If a message is 160 characters or less, it is billed as one message. If it is longer than 160 characters, it is a long message and is split and billed as multiple messages based on 153 characters per message. The signature for pure English messages uses Example: A message with 350 characters is split into three messages of 153, 153, and 44 characters, and is billed as three messages. |
Messages in other languages (UCS-2 encoding) | Chinese characters, letters, numbers, symbols, and spaces are all counted as one character. If a message is 70 characters or less, it is billed as one message. If it is longer than 70 characters, it is a long message and is split and billed as multiple messages based on 67 characters per message. Example: A message with 150 characters is split into three messages of 67, 67, and 16 characters, and is billed as three messages. | |
You cannot directly modify an approved message template that exceeds 70 characters. Instead, you must create and submit a new, shorter template for approval.
Rate limit
A maximum of 20 messages can be sent to a single phone number per day.
To avoid sending too many messages to a single phone number, you can configure a daily limit. For more information, see frequency settings.
There is no default suspension threshold for international SMS. You must configure a threshold based on your actual usage to prevent financial losses from SMS pumping. For more information, see verification code anti-fraud.