The phrase "got on the horn" is a colloquialism for "made a phone call." There are several other commonly used phrases that can be used as synonyms for this term, including "made a call," "dialed up," "rang up," "phoned in," "placed a call," "picked up the phone," "made a quick call," or simply "called." These phrases can be used interchangeably to convey the same meaning, whether it's for a casual or formal conversation. Choosing the right synonym for "got on the horn" will depend on the tone and context of your conversation, as well as your audience.