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

1. From Yahoo! Messenger’s main menu, select Preferences.
2. Select the Connection category.
3. If “Use an HTTP proxy” is visible and checked, you might not be able to use voice. You can try unchecking it and see if Yahoo! Messenger will connect.

Yahoo! Messenger will work if any one of these TCP ports is open:

• 5050
• 443
• 80

At least ONE of these ports must be open in order to use Yahoo! Messenger’s voice features: PC-to-PC voice conversations, Yahoo! Phone Out calls, or incoming phone calls ( Yahoo! Phone In).