In standard Mobile Station International Subscriber Directory Number (MSISDN) format, a numeric Sender ID is the default sender type for an SMS message. A numeric sender ID can be used for two-way messages since recipients can react to messages with it.

A Sender ID is a numeric or alphanumeric identifier for the person who sent an SMS message. Sender IDs display at the beginning of text message discussions and assist users in determining which company delivered a certain message.