1. To begin or commence (something). It's time to ring up the curtain on this new project, everyone, so let's not waste any time! After a few delays, the construction crew was finally ready to ring up the curtain.

2. To make (something) publicly known; to reveal or disclose the truth (about something). In an attempt to head off a public relations disaster regarding his acceptance of donations, the governor decided to ring up the curtain at a press conference.