Parameter Name,Description,Reference
sfua-id,"The URN identifying the User Agent, constructed as specified         
in section 4.1 of [RFC5626] ""Managing Client-Initiated
Connections in the Session Initiation Protocol (SIP)"".
Since the procedure defined by [RFC5626] allows any UA to
construct a value for this parameter, the sfua-id parameter
MUST always be included.
If the UA implements [RFC5626], and includes the
'+sip.instance' Contact header field parameter in any request,
when requesting configuration it MUST use the same value for
the sfua-id parameter.",[RFC6011]
sfua-user,"An identifier for a user associated with the configuration. Note     
that this might be different than any SIP 'user' in the UA
configuration: it could, for example, be the login name of an
account on the service provider web site.  The syntax of this
parameter is that of the [RFC2617] 'userid'.
See Section 2.4.1, ""Configuration Data Request Authentication"" for
how this parameter relates to authentication of the configuration
data request.",[RFC6011]
sfua-vendor,"An identifier that specifies the vendor of the User Agent.  The      
syntax of the value of this parameter is that of a DNS domain.
The domain value MUST be that of a domain owned by the vendor.",[RFC6011]
sfua-model,"An identifier that further specifies the User Agent from among
those produced by the vendor.  The syntax of the value of this
parameter is the same as the [RFC3261] 'token'.  Values for this
parameter are selected by the vendor.",
sfua-revision,"An identifier that further specifies the User Agent from among       
those produced by the vendor.  The syntax of the value of this
parameter is the same as the [RFC3261] 'token'.  Values for this
parameter are selected by the vendor.",[RFC6011]