The opt-in option is linked with getting authority from the subscriber to send promotional materials and messages to his or her’s email, mobile number or chat application.
The opt-in function mostly is used by marketing departments to tell unique promotional offers, hot deals or changes in terms and conditions. Often, the opt-in choice is offered by zero rated short codes which signifies that the user can opt-in without any extra cost per message.
Opt-in is closely linked with opt-out so the user can unsubscribe from the messages he gets.
The procedure of using the opt-in varies worldwide and in some countries the opt-out function is an obligatory part of message text. Instructions on how to opt-out are provided at the end of a message. Apps for chat like Viber have an opt-out option for A2P messages at the top of the chat group.