Meta-owned WhatsApp has put out a detailed FAQ on its upcoming username feature, addressing concerns around impersonation, scams and unwanted contact as users begin reserving usernames.The FAQ comes days after the Centre issued a notice to Meta, flagging fraud and impersonation risks and asking the company to hold off on the rollout until consultations are completed "to the satisfaction of the government."Also read: Worries arise over gaming of WhatsApp usernamesThe feature will let users create unique usernames to connect on WhatsApp without sharing their phone number.Q: Are usernames mandatory?A: Nope, they are optional.Q: What if the username I want isn't available?A: There's a few reasons you might not be able to reserve the username you want:1) It's an existing Instagram or Facebook username; these are reserved for their owners.2) We've held well-known names and some variations of them -- like public figures, celebrities, government entities and Meta-verified accounts - so they can only be claimed by their legitimate owners. If you try to reserve those, the system will say it's not available.3) Someone already claimed a common name, in that case use the username generator.Q: What if someone creates a username similar to mine to impersonate me or run a scam, how do you stop someone from pretending to be me?A: Usernames are not available for messaging yet. When they are, and you get a message from someone new, we'll let you know the country origin, and a warning for first time outreach. Well-known public-figure names and their variations are held for verified owners. We're also keeping a close eye on blocks and reports to take action against scammers.Q: Can random people message me if they know or guess my username?A: Just like you can't search for a phone number in WhatsApp, you can't search for a username. The best way to prevent someone from contacting you is to add a username key and to choose a username that is unique to WhatsApp.Also read: How to manage business chats on WhatsAppAll the current measures remain in place to prevent unwanted contact, including warnings with details about unknown senders (whether they're a new account, if you share groups, what country they're in) and the ability to block and report.Q: What is a username key?A: An extra layer of protection you can enable with your username, so that another user will have to know both your username and your username key to contact you. You can reset your key at any time to stop new inbound contact through your username.Q: Do I have to link my other Meta accounts?A: If you want the same username as your Instagram or Facebook account, you'll have to link them. This is one of the ways to reduce impersonation and to make sure you're the legitimate owner of the account. But after that, you can unlink the account if you want, or you can choose a username unique to WhatsApp.Q: Can I change my username later?A: Yes, as long as the new one you want is available.WhatsApp added that claims about popular or well-known usernames being reserved by anyone other than their legitimate owners are false. It said reservations were opened ahead of the feature's formal launch later this year since people are likely to feel strongly about their chosen username, and that it is taking time to factor in feedback before the wider rollout. With inputs from PTI