This topic describes the rules for sending messages from Short Message Service (SMS). These rules include message length and delivery frequency.

Length rules

A message can be a maximum of 1,500 characters in length. Each letter, digit, symbol, or Chinese character is calculated as one character.

  • English

    Each letter, digit, or symbol is calculated as one character.

    If a message contains no more than 160 characters, you are charged for one message. If a message contains more than 160 characters, it is split into multiple messages that have a maximum length of 153 characters. A signature is enclosed in brackets ([ ]).

    Example: If a message contains 350 characters, it is split into three messages. The first two messages contain 153 characters each and the last message contains 44 characters.

  • Other languages

    Each letter, digit, symbol, or Chinese character is calculated as one character.

    If a message contains no more than 70 characters, you are charged for one message. If a message contains more than 70 characters, it is split into multiple messages that have a maximum length of 67 characters.

    Example: If a message contains 160 characters, it is split into three messages. The first two messages contain 67 characters each and the last message contains 26 characters.

Delivery frequency

To limit the number of messages that you can send to an individual mobile number each day, Alibaba Cloud allows you to configure the daily delivery frequency of messages. A maximum of 20 messages can be sent to each mobile phone number per day.

For more information, see Configure the message delivery frequency.