Layer
Session L5
Dialogs, call state, session control.
Q.931
Lab readyISDN user-network call control: SETUP, CALL PROCEEDING, ALERTING, CONNECT, DISCONNECT, RELEASE. Information elements carry bearer capabil…
H.323
Lab readyITU umbrella for packet multimedia: H.225.0 call signaling/RAS, H.245 media control, and RTP/RTCP media. Gatekeepers provide admission an…
SIP
Lab readyText-based signaling for creating and managing sessions. Methods (INVITE, ACK, BYE, REGISTER…) and response codes resemble HTTP; SDP bodi…
SDP
Lab readyTextual session description: media lines, codecs (rtpmap/fmtp), ICE candidates, and direction attributes. Carried in SIP, WebRTC, and MGC…
OPC UA
Lab readyPlatform-independent industrial information model with secure channels, sessions, subscriptions, and monitored items. Binary UA-TCP and H…
TCAP
Lab readyTransaction and dialogue layer over SCCP for intelligent-network and mobile services. Begin/Continue/End/Abort components carry MAP, CAP,…
MGCP
Lab readyMedia Gateway Control Protocol in which Call Agents issue CRCX/MDCX/DLCX and signal requests to subordinate media gateways. SDP in the te…
H.248 / Megaco
Lab readyH.248/Megaco media-gateway control using terminations, contexts, and descriptors for large carrier gateways. It succeeds MGCP conceptuall…
Skinny (SCCP)
Lab readyCisco Skinny Client Control Protocol (SCCP) for phone registration and call control toward CUCM. Station messages drive lamp, ringer, and…
ICE
Lab readyInteractive Connectivity Establishment gathers local, reflexive, and relay candidates, then runs STUN checks to pick working media paths.…
WebRTC Signaling
Lab readyApplication-defined signaling — often SIP, or JSON over WebSocket — that exchanges SDP offers/answers and ICE candidates for WebRTC peers…
H.225.0
Lab readyH.323 call signaling and RAS: Q.931-derived Setup/Alerting/Connect on the Call Signaling Channel plus gatekeeper discovery/registration. …
H.245
Lab readyH.323 multimedia control protocol for capability exchange, master/slave determination, and logical channel open/close. Fast Start and H.2…
HTTP/2
Lab readyMultiplexed binary framing over a single TLS/TCP connection with streams, HPACK headers, and flow-control windows. It underpins gRPC and …
TLS
Lab readyTransport Layer Security provides a record layer and handshake for confidentiality and integrity on TCP apps. Certificates, AEAD ciphers,…
DTLS
Lab readyDatagram Transport Layer Security adapts TLS to unreliable transports with retransmission, explicit sequence numbers, and record epochs. …