rection Server Unless stated otherwise, the protocol rules for the INFO request at a proxy are identical to those for a BYE request as specified in [1]. 3. INFO Message Bodies The purpose of the INFO message is to carry mid-session information between SIP user agents. This information will generally be carried in message bodies, although it can be carried in headers in the INFO message. The definition of the message bodies or any new headers created for the INFO method is outside the scope of this document. It is expected that separate documents will be created to address definition of these entities. Donovan Standards Track [Page 6] RFC 2976 SIP INFO Method October 2000 In addition, the INFO method does not define additional mechanisms for ensuring in-order delivery. While the CSeq header will be incremented upon the transmission of new INFO messages, this should not be used to determine the sequence of INFO information. This is due to the fact that there could be gaps in the INFO message CSeq count caused by a user agent sending re-INVITES or other SIP messages. Guidelines for extensions making use of INFO The following are considerations that should be taken into account when defining SIP extensions that make use of the INFO method. Consideration should be taken on the size of message bodies to be carried by INFO messages. The message bodies should be kept small due to the potential for the message to be carried over UDP and the potential for fragmentation of larger messages. - There is potential that INFO messages could be forked by a SIP Proxy Server. The implications of this forking of the information in the INFO message need to be taken into account. - The use of multi-part message bodies may be helpful when defining the message bodies to be carried by the INFO message. - The extensions that use the INFO message MUST NOT rely on the INFO message to do anything that effects the SIP call state or the state of related sessions. - The INFO extension defined in this document does not depend on the use of the Re