Yahoo! Phone Out Setup and Usage

• What are the system requirements to use the premium Yahoo! Voice services?
• Can I use Yahoo! Voice services from behind a firewall?
• Can I use Yahoo! Voice services on a different Mac, such as at an Internet café?
• How can I change the sound volume?
• Can I make a Test Call before signing up?
• How do I make international calls in Yahoo! Messenger?
• How do I make domestic calls in Yahoo! Messenger?
• Can I call mobile telephone numbers?
• Can I call 411, 555-1212, and other Directory Assistance or operator-assisted numbers?
• Can I dial using letters?
• What kinds of firewalls are supported to use Yahoo! Voice services?
• What ports are used by Yahoo! Voice services?
• Does it matter if I have a slow or fast network connection when using Yahoo! Messenger PC-to-PC voice service?
• What kinds of network address translators (NATs) are supported to use the Yahoo! Voice services?
• Why is there an echo?
• Why is the other person’s voice choppy?
• I can't hear or be heard.
• I am unable to use the Yahoo! Voice services due to a connection problem. What might be causing this?
• Why can't I connect to the voice servers?