If your contacts want to interact into the flow, they should be initialized. A flow can be initialized in different ways:

• You can initialize manually a flow when you want through the box “Start a flow” on the flow editor;
• Your contacts can initialize a flow receiving a keyword;
• A flow can be started in a future date or a scheduled;
• A flow can be started through a campaign event;
• A flow can be started after a lost call;
• A flow can be started after a received call;
• A flow can be started after receiving a message not handled elsewhere.