Why is this a thing? Why do you have chat, text, AND party invite privacy setting bundled...

You should also check to see what your privacy settings are set to.

• Go into your settings screen
• Click on account
  • Click on Privacy and Safety
• Click on App Privacy
  
• Go to "Microphone"
  
• Set it to on if it isn't already
  

Alternatively;

• Go to settings
• Click on account
  • Click on Privacy and Safety
• Click on Xbox Live Privacy
  
• Click on View Details and Customize
  
• Click on Communication & Multiplayer
  
• Make sure that both "Others can communicate with voice, text or invites" and "You can communicate outside Xbox Live with voice and text" are NOT
  set to block.
  

You can do it in the online safety settings on the Xbox one by going to settings 》 account 》privacy and online safety or by going to this link: http://account.xbox.com/settings

Make sure this setting is set to friends or everyone:

Others can communicate with voice, text, or invites.

Also do you have an adult or child account, as parental controls might be blocking it

You can can change your privacy settings by

1. Going to https://account.xbox.com/en-US/settings/home? and click privacy settings.
2. Then scroll down to "Others can communicate with voice, text, or invites?" and select "Everyone"
3. Scroll down to the bottom of the page to save

Hope this helps!

Hi there! This is Virginia O.

I understand that you want to talk to your friends however they can't hear you.

I apologize for the inconvenienced this has caused you. I will do my best to help you.

Please check privacy settings. Go to Settings > Account > Privacy & online safety > Xbox privacy and make sure that "Others can communicate with voice, text, or invites" is set to "Everyone".

And then check party settings. If you're in a party, make sure your microphone is not muted. Press the Xbox button to open the guide, go to Parties & chats, and check the microphone icon.

Next is to update your console. Go to Settings > System > Updates and check for updates.

Then restart your console and router.Kindly unplug your Xbox console and router from the power source, wait a few seconds, and then plug them back in.

Kindly test your microphone. Go to Settings > Devices & connections > Accessories and select your microphone to test it.

If incase that your friends can't hear you, try using a different headset or controller to see if the issue persists. This will be a great help to determine if there's a hardware malfunction.

Thank you for your cooperation.

Whether players can chat using text or voice is up to the developer. You will still have to have the privacy settings on your account set correctly to allow it. You should pose these questions to Roblox.

Children's accounts may have it disabled by default until a parent approves it, but I don't have direct experience with that.

And early example of this was when Infinity Ward blocked users in party chats from COD MW2 multiplayer on 360 because it was being used to coordinate people sabotaging the other team.