Features of Skype "SkypeIn") allows a Skype user to receive calls to their Skype client (on whatever device) dialed from mobiles or landlines to a Skype-provided phone number. The number need not be in the same location as the user. For example, a user in San Francisco could create a local telephone number in London. Callers in London could then make a local call to reach that user (who answers on Skype in San Francisco). Skype offers numbers in Australia, Chile, Denmark, Estonia, Finland, France, Germany, Hong Kong, Hungary, Ireland, Italy, Republic of Korea, Malta, Mexico, Netherlands, New Zealand, Poland, Romania, South Africa,
Skype to be an effective method for identifying Skype's TCP- and UDP-based protocols. Skype 2.x used G.729, Skype 3.2 introduced SVOPC, and Skype 4.0 added a Skype-created codec called :SILK, intended to be "lightweight and embeddable". Additionally, Skype has released Opus as an open-source codec, which integrates the SILK codec principles for voice transmission with the CELT codec principles for higher-quality audio transmissions, such as live music performances. Opus was submitted to the Internet Engineering Task Force (IETF) in September 2010. Since then, it has been standardized as RFC 6716 VP7 is used for versions prior to Skype 5.5. As of