Call info. This field contains additional information about the caller, depending on whether it is found in a request or response. The purpose of the URI is described by the “purpose” parameter. The “icon” setting refers to an image that can be considered an iconic representation of the caller or caller. The “info” setting describes the caller in general, z.B. via a web page. The “Card” setting provides a business card, z.B. in vCard or LDIF formats. Additional chips can be saved with IANA. The use of the Call-Info header field may pose a security risk. When a caller retrieves URLs provided by a malicious caller, there may be a risk of reporting inappropriate or offensive content, dangerous or illegal content, etc.
Therefore, it is RECOMMENDED that an AU returns the information to the info call header field only when it can verify the authenticity of the item created by the header field and trust that element. It is not necessarily the UA peer; A proxy can insert this header field into the requirements. Info alert. If you have a DEMANDE request, the alert field indicates an alternative ringtone to the UAS. If a ringing response is displayed, the alert field indicates an alternative ringtone to the UAC. A typical use is that a proxy inserted this header field to provide a distinctive ring function. The alert field can lead to security risks. In addition, a user can selectively disable this feature. sec-agree. This option date indicates support for the security agreement mechanism. If used in Heads Require or Proxy-Require, this indicates that proxy servers are needed to use the security mechanism.
If used in the supported header, it indicates that the user agent`s client is supporting the security mechanism. If used in the header requires in answers 494 (security agreement required) or 421 (Extension Required), this indicates that the user agent`s client must use the security mechanism. Answer 494 Security Agreement Required  is used to deny a requirement containing a “Require: sec-agree” header under the security agreement mechanism. The core of the UAC. (RFC 3261) All processing functions required by a UAC above transaction and transportation levels. The package of events. (RFC 3265) An event package is an additional specification that defines a series of status information to be reported by a flight group to a subscriber. Event packets also define additional syntax and semantics based on the framework set out in this document, which is required to transmit this status information. server. Contains information about the software used by the UAS to process the application. Detecting the specific version of the server software can allow the server to become more vulnerable to attacks on software that is known to contain security vulnerabilities.