This topic describes the length limit of a Short Message Service (SMS) message and how SMS processes a long message.

Message blocking rules

  • For information about the service terms of SMS, see Terms of Service.
  • SMS checks international SMS messages by using a system security module. In addition, system monitoring is applied to prevent message content from violating local national laws and regulations.
  • If a message that contains illegal content is found, the account that is used to send the message is frozen. The deposit is deducted from the account and the user is subject to legal liabilities.
  • After the account is frozen, the user can no longer use SMS. The SMS resource plans or coupons of the account are not available. The account cannot be subsequently activated and used.

Message length limits

Note The length limit of an SMS message is determined by character encoding. The maximum size of an SMS message is 1,280 bits or 160 bytes based on international standards.

The following message length limits are applied based on languages:

  • English: 7-bit ASCII encoding is used for English messages. Each message can be up to 160 bytes in length.
  • Other languages: Unicode encoding is used for messages in other languages. Each character occupies 2 bytes of space regardless of full or half width. Each message can be up to 70 characters in length.

Long message processing

The following processing methods of long messages are used based on languages:

  • English:
    • Each letter, digit, or symbol is calculated as one character.
    • If a message contains at most 160 characters in length, you are charged for one message. If a message contains more than 160 characters in length, SMS considers the message as a long message. A long message is separated into multiple messages for billing and each message contains at most 153 characters. Each signature is enclosed in brackets [].

      For example, if a message contains 350 characters in length, the message is separated into three messages. The first message contains 153 characters, the second message contains 153 characters, and the third message contains 44 characters.

  • Other languages:
    • Each letter, digit, or symbol is calculated as one character.
    • If a message contains at most 70 characters in length, you are charged for one message. If a message contains more than 70 characters in length, SMS considers the message as a long message. A long message is separated into multiple messages for billing and each message contains at most 67 characters.

      For example, if a message contains 160 characters in length, the message is separated into three messages. The first message contains 67 characters, the second message contains 67 characters, and the third message contains 26 characters.