Customers who connect through a firewall or proxy server might not be able use the voice feature. Here's how to determine if this applies to you:

1. Click Messenger in Yahoo! Messenger and select Preferences.
2. Click "Connection".
3. If anything other than "No proxies" is checked, you might not be able to use voice feature. You can try selecting "No proxies" and see if Yahoo! Messenger will connect.

As for TCP ports, Yahoo! Messenger will work if any one of these TCP ports are open:

• 5050
• 443
• 80

At least ONE of these ports must be open in order to make PC-to-PC or PC-to-phone (Phone Out) calls, or to receive calls (Phone In).