Cisco systems is expected to make an announcement about integration of Session Initiation Protocol (SIP) into all of the company's future voice-over-IP products some time tomorrow. SIP, a signalling protocol for Internet conferencing, telephony, presence, events notification and instant messaging, is also an IETF standard that enables VoIP products to recognize point-of-presence, IP-based conferencing, and instant messaging capabilities already used by other VoIP components.