Yealink SIP-T19 E2 T4 Series, Руководство администратора

Страница: 14 / 981

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series IP Phones
xiv
firewalls like to know what applications are flowing through which ports and it is possible to use
content types of other applications other than the one you are trying to let through what has
been 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 issue
multiple responses to the UAC, not necessarily a single response. Communication between UAC
and 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 only
as one or the other per transaction. Whether the endpoint functions as a UAC or a UAS depends
on the UA that initiates the request.