What Hung Up refers to
The lobby phone is separate from map voting, the shop, and combat. The current player guide reports that answering the ringing phone before another player can earn the Hung Up badge. The exact trigger and timing are not independently confirmed by a public developer note, so treat this as a lead to test in the live experience rather than a guaranteed unlock.
A low-risk attempt
Stay in the lobby between rounds and watch for the phone to ring. If you are pursuing the badge, move to the phone and use the interaction prompt your Roblox client displays. Do not assume a keyboard letter, cooldown, or fixed spawn interval; those details can vary or may not be documented.
Check the result
After the interaction, check the Roblox badge interface or the in-game confirmation. If another player reaches the phone first, wait for a later opportunity instead of repeatedly activating it. A missed attempt does not change the normal survival objective.
Avoid false instructions
The phone is not a promo-code box or a combat tool. Ignore videos that promise a guaranteed badge through a specific unverified keybind or exploit. If the phone UI or badge requirement changes in an update, trust the live prompt and re-check the game before relying on an older route.