First and foremost, go back and read the other guides on the site related to our voice chat server. Many settings and helpful hints can be gleaned from simply reading the other guide
Unable to Connect
Try the link in the "Our Server" guide. If this works, you have entered incorrect information in the server settings. You will need to disconnect, click connect, select our server, right click and select edit, and change the Server Settings to the correct values. Pay close attention to the address and port fields.
If the link in the "Our Server" guide did not work, then check your username. If you specify an invalid username (see "Our Server" guide), you will not be able to connect to the server.
People Are Unable to Hear Me
First run the Audio Wizard (or Audio Statistics). Can you hear yourself during the Audio Wizard (or see speech in the Audio Statistics)? If not make sure the Audio Device is set to the correct device. If the audio device is set correctly, something is wrong with your device drivers or hardware.
If the Audio Wizard (or Audio Statistics) show they are reading your microphone correctly, take a look into the settings of any hardware or software firewalls between you and the internet. Many Anti-Virus and Anti-Spyware products include a firewall and will block the communication of programs they do not know (such as mumble). If you use these products, ensure port 64738 is open (allowed) for both incoming and outgoing TCP and UDP traffic. Traditionally mumble uses TCP for control data and UDP for voice data.
I Sound Like Megatron
This can happen in a noisy environment. Make sure the area around your microphone is clear of loud background noises and try lowering the amplification on your microphone or changing the noise suppression settings.
Another thing to check is your latency (ping) when connecting to the server. If the latency is high, you can try adjusting the "jitter buffer" under audio output or the audio compression settings. If the latency of your internet connection is high, there may be nothing you can do other then switch to a higher speed internet provider.
Remember, once your account has been registered on the server, the username cannot be changed. If you are trying to change your username and have authenticated talk to one of the Mumble server administrators. I would recommend having a good reason ready.
If your account is not registered, often simply changing the username setting on the "Mumble Server Connect" page will fix problems related to your username. When starting mumble, right click on the name of the server you use and select "Edit Settings". Make sure the new username you wish to use is listed.
If you have an authenticated account and have a backup of your certificate, try importing the backup copy of your certificate. This will usually fix any issues where the certificate stored in the Mumble client's database has become corrupt.
No Luck? First and foremost: go backup your certificate for mumble now! Once you have backed up the certificate using the "Certificate Wizard", uninstall mumble from the computer. Make sure you tell the uninstaller to remove all settings and preferences.
Next, restart the computer and install mumble. If your account was previously registered on the computer, import your certificate back into mumble, otherwise simply create a new certificate.
Feedback occurs when a sound loop exists between an audio input and an audio output. This often results in a high pitched squealing sound. If the sound occurs when a single user is talking, the cause is often resolved by changing the placement of the microphone and speakers in use. If two people are trying to talk, this can be caused by a feedback loop between the two users, and the easiest remedy is for both people to configure push to talk or change the sensitivity of their microphones.