Abstract: The session initiation protocol (SIP) is used to establish calls/sessions between end-points. The type of session to be established is described by the session description protocol (SDP), RFC 2327. At present however, RFC 2327 only contains parameters that describe audio or video sessions. The expansion according to the invention of the SDP by corresponding parameters that describe file sharing sessions thus permits file sharing sessions to be established using the SIP.

Abstract: The invention relates to a method for transmitting data packets containing private Internet addresses. In prior art, the transmission of data packets containing private IP addresses is problematic, as said addresses are not unequivocal on a world-wide basis. According to the invention, at least one field is provided in the information block of an IP packet which can accommodate an identification that indicates a private network which is unique world-wide. This identification determines the interpretation of the subsequent (private) IP addresses.