The duration of a Roblox voice chat depends on the violation of Community Rules or Terms of Use you have committed. Some bans may get lifted after 24 hours while some can even be permanent. Usually, Roblox voice chat bans last less than a week. If you got banned from Roblox voice chat after committing a violation of its rules, make sure to stick to the rules of the platform. There is a high chance to get permanently banned from the voice chat if you repeat the same mistakes. Roblox is a platform for entertainment and creativity, so any sort of harmful or unpleasant behavior will be promptly addressed by the developers of Roblox to keep the platform safe & clean.