60202 Domain name using TCP transport and ; bbranch=z9hG4bK776a port number 60202 Via: SIP/2.0/UDP 120.121.122.123 Proxy added Via header field with ; branch= z9hG4bk56a234f3.1 branch V : SIP/2.0/UDP proxy.garage.org Compact form with domain name ; branch= z9hG4bK3423423a3.3 using UDP; third search location of forking proxy Via: SIP/2.0/TCP 192.168.1.2 The address is a multicast address. ; received=12.4.5.50 branch=z9hG4bK334 IPv4 address is nonglobally unique. Request has been forwarded through a NAT, which changed the IP address to a globally unique one. Via:SIP/2.0/UDP host.user.com: 4321 The address is a multicast address ;maddr=224.1.2.3 ;ttl=15 specified in maddr with a specified ; branch=z9hG4bK341344 6.2 Request Header Fields This set of header fields can only be present in a request. 6.2.1 Accept The Accept header field is defined by HTTP [2] and is used to indicate acceptable message Internet media types [13] in the message body. The header field describes media types using the format type/sub-type commonly used in the Internet. If not present, the assumed acceptable message body for- mat is application/sdp. A list of media types can have preferences set using q value parameters. The wildcard "*" can be used to specify all sub- types. Examples are given in Table 6.12. 6.2.2 Accept-Contact The Accept-Contact [4] header field specifies to which URIs the request may be proxied. Some additional parameters are also defined for Contact SIP Header Fields Table 6.12 Examples of Accept Header Field Header Field Meaning Accept: application/sdp This is the default assumed even if no Accept header field is present Accept text/* Accept all text encoding schemes Accept: application/h.245;q=0.1 Use SDP if possible, otherwise, use H.245 application/sdp;q=0. header fields such as media, duplex, and language. This header field is part of the caller preferences extensions to SIP, which have been defined to give some control to the caller in the way a proxy server processes a call. The compact form is a. Some examples foll