A broadband Internet connection is recommended. However, the actual broadband speed is not very important.

When an audio signal, like the sound of your voice during a phone call, is sent over the Internet, the sound is first compressed so that it will use less network bandwidth. When the audio signal arrives at the other end, it is decompressed so that it can be heard. Some audio fidelity is lost in this process. The audio stream is less compressed with a broadband connection than with a dial-up connection, so the sound quality is higher. The difference is slight, however, and is often unnoticeable.

During a call, Yahoo! Messenger continuously monitors the voice quality and dynamically reduces or increases the amount of compression. This ensures maximum sound quality, based on your actual bandwidth.