SIP

(1) (Session Initiation Protocol) An IP telephony signaling protocol developed by the IETF. Primarily used for voice over IP (VoIP) calls, SIP can also be used for video or any media type; for example, SIP has been used to set up multi-player Quake games. With SIMPLE extensions for IM and presence, SIP is also used for instant messaging (see SIMPLE).

SIP is a text-based protocol that is based on HTTP and MIME, which makes it suitable and very flexible for integrated voice-data applications. SIP is designed for real-time transmission, uses fewer resources and is considerably less complex than H.323. Its addressing scheme uses URLs and is human readable; for example: sip:john.doe@company.com.

SIP relies on the session description protocol (SDP) for session description and the Real Time Transport Protocol (RTP) for actual transport (see RTP and SDP). Windows XP was the first version of Windows to natively support SIP for PC-based phone applications, and numerous vendors make SIP desktop phones. See SIP proxy.

(2) (SiP) (System in Package) A complete system packaged in one housing. A SiP contains several ICs (chips) including a microprocessor on a single substrate such as ceramic or laminate. A SiP is really a multichip module (MCM) that contains all the parts of a complete system. The SiP term was first used by Amkor Technology in the late 1990s and not trademarked in order to encourage its use worldwide. See SoC and MCM.

System In Package
This cross section of a SiP shows a microprocessor (µP), SRAM and flash memory chips packaged together in the same housing. The L,R,C stands for inductor, resistor, capacitor. (Image courtesy of Amkor Technology, Inc.)

(3) (Single In-line Package) A type of chip module that is similar to a SIMM, but uses pins rather than edge connectors. SIP is sometimes spelled SIPP (Single In-Line Pin Package). See SIMM.

SIP Module
SIPs use pins to plug the module into the socket whereas SIMMs and DIMMs use edge connectors like ISA and PCI plug-in cards.

(4) (SMDS Interface Protocol) The protocol used to support SMDS service. It is composed of the Level 3 Protocol Data Unit (L3_PDU), which contains source and destination addresses and an information field up to 9188 bytes long. See SMDS.

(5) (Software Integration Platform) A specification that provides a common format and interface for storing and retrieving geographic data for the petroleum industry.

1.	(protocol)	SIP - Session Initiation Protocol.
2.	(text, standard)	SIP - Supplementary Ideographic Plane.