Product Overview3firewalls like to know what applications are flowing through which ports and it is possible to usecontent types of other applications other than the one you are trying to let through what hasbeen denied.User Agent Server (UAS)UAS is a server that hosts the application responsible for receiving the SIP requests from a UAC,and on reception it returns a response to the request back to the UAC. The UAS may issuemultiple responses to the UAC, not necessarily a single response. Communication between UACand UAS is client/server and peer-to–peer.Typically, a SIP endpoint is capable of functioning as both a UAC and a UAS, but it functions onlyas one or the other per transaction. Whether the endpoint functions as a UAC or a UAS dependson the UA that initiates the request.Phone ModelsThis section introduces T48G/T46G/T42G/T41P/T40P Skype for Business phone models. Theyare designed to work with Skype for Business Server. These Skype for Business phones arecharacterized by a large number of functions, which simplify business communication with ahigh standard of security.The T48G/T46G/T42G/T41P/T40P Skype for Business phones provide a powerful and flexible IPcommunication solution for Ethernet TCP/IP networks, delivering excellent voice quality. Whenthese phones register Skype for Business accounts, you can interact with your Skype forBusiness contacts list on your phones through Microsoft’s Active Directory.Skype for Business phones comply with the SIP standard (RFC 3261), and they can only be usedwithin a network that supports this model of phone.For a list of key features available on Yealink Skype for Business phones running the latestfirmware, refer to Physical Features of Skype for Business Phones on page 4.In order to operate as SIP endpoints in your network successfully, Skype for Business phonesmust meet the following requirements: A working IP network is established. VoIP gateways are configured for SIP. The latest (or compatible) firmware of Skype for Business phone is available. The Skype for Business Server is active and configured to receive and send SIP messages.
