sign on

Noun

• The time of day when a radio or television station begins broadcasting, usually after being off the air for several hours.
• Alternative of sign-on

Verb

• To join something, after signing.
• To commit oneself, as to a project, a goal, on organization, a cause.
• To begin broadcasting a radio or television signal, usually at the beginning of a broadcasting day and after being off the air for several hours.
• To log on; to start using a computer, radio, etc., or to start talking.
• To apply to receive unemployment benefits.