voip-secure
TRANSCRIPT
Audio Codecs Video Codecs
G.711 G.728
G.722 G.729
G.723.1 G.726
H.261
H.263
H.264 MPEG-4
MGCPMedia GatewayControl Protocol
SGCPSimple GatewayControl Protocol
H.248MEGACO
Media GatewayControl
GCP SIP
SDPSession
DescriptionProtocol
SAPSession
AnnouncementProtocol
H.323
SIP SessionInitiationProtocol
H.225.0RAS
RegistrationAdmission
Status
H.245Call Control
H.225.0Q.931
Call SetupRTSP
Real TimeStreamingProtocol
RTCPReal Time
ControlProtocol
NCSNetwork-BasedCall Signaling
Other
Cisco SCCPSkinny Client
ControlProtoc ol
TCP/UDPUDP/RUDP
Media Control SignalingApplications
SkypeSignaling
TCP/UDP
SCTPStream ControlTransmission
Protocol
cRTPCompressed Real Time Protocol
RTPReal TimeTransportProtocol
H.235Security
IPDCIP Device
Control
AAA
IPDRInternet Protocol
Detail Record
OSPOpen Settlement
Protocol
Real-timeConferencing
T.120
FoIPFacsimile over IP
T.38
H.450Supplement
Services(e.g.,Call Waiting)
MoIPModem over IP
V.150
Services
RADIUSRemote Authenticaion Dial-In User Service
IP
VOIP Quick GuideVOIP Quick Guide
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VOIP Architecture
VOIP Protocols
Authentication Authorization Accounting
PSTN
Internet
LANLAN
Gateway
WAN
MediaGateway
SoftSwitch
H.323Gatekeeper
Gateway
Gateway
Router
Router
H.323Gatekeeper
H.324Multimediaover POTS
H.320Multimediaover ISDN
GCPPhone
GCPTerminal
GCPPhone
SIPTerminal
SIPTerminal
SIPPhone
Router
H.323Phone
H.323Terminal
H.323Phone
H.323Terminal
SIPServer
Gateway
Router
Class 5Switch
SS7 Signaling
GCP Signaling
SIP Signaling
H.323 Signaling
RTP Traffic
PSTN Traffic
ISDNPhone
POTSPhone
LANLAN
MSUMediaGateway
SignalingGateway
SoftSwitch
Router
Router
H.323 Network Architecture
Gateway Control Protocol (GCP)Network Architecture
Session Initiation Protocol (SIP)Network Architecture
SIPServer
Router
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VOIP Technology Comparison
Standards body
Architecture
Call control
Endpoints
Signaling transport
Multimedia
Media transport
DTMF-relay transport
Fax-relay transport
Supplemental services
H.323
ITU-T
Distributed
Gatekeeper
Gateway, terminal
TCP/UDP
Yes
RTP-Real Time Transport Protocol
RTP
T.38
By endpoints or call control
SIP
IETF
Distributed, Peer-to-Peer
Proxy/Redirect Server
User agent
TCP/UDP
Yes
RTP-Real Time Transport Protocol
RTP
T.38
By endpoints or call control
MGCP/H.248/Megaco
MGCP/Megaco by IETF; H.248 by ITU-T
Centralized
Call agent/Media Control Gateway / Softswitch
Media Gateway, dump terminal
MGCP - UDP H.248/Megaco-TCP/UDP
Yes
RUDP - Reliable User Datagram Protocol; RTP - Real Time Transport Protocol
RTP
T.38
By call agent
H.323 - A Distributed VOIP NetworkH.323 Network Elements
Terminals: a network endpoint which may provide audio, data and video, communicat ions with another H.323 terminal. Gateways: a network funct ion that provides access to terminals on a circuit switched network (such as the PSTN) or another H.323 network. Gatekeepers: a network funct ion that provides address translat ion, access control, bandwidth management, and other management operat ions.Multipoint Control Units: a network funct ion that allows three or more terminals to part icipate in a mult ipoint conference.
H.323 gatewayH.323 gatkeeper
H.225 TCP connect ion
SETUP
CONNECT (H.245 address)
H.245 TCP connect ion
Capabilit ies exchange
RTCP address
CONNECT (H.245 address)
RTCP addresses
RTCP&RTP addresses
RTP stream
RTP stream
H.323 gateway IP phone
H.245signaling
H.225signaling
Example H.323 Call Flow ITU-T H.323 Standards
Standard#
H.323
H.225.0
H.235
H.239
H.245
H.246
H.350
H.360
H.450
H.460.x
H.501
H.510
Description
For secur ity in H.323 network.
H.323/PSTN Interworking.
Supplements in H.323.
Mobility for H.323 multimedia systems.
An umbrella recommendation of ITU-T thatdefines the protocols to provide audio-visual communication sessions on any packet network.
For call signaling, the media (audio and video), the stream packetization, media stream synchronization and control message formats.
For dual stream use in videoconferencing.
A control protocol for multimedia communication.
Directory Services Architecture for Multimedia Conferencing.
An architecture for end-to-end QoS control and signaling.
For supplementary services such as call waiting, call forwarding, etc.
Protocol for mobility management and intra/inter-domain communication in multimedia systems.
SIP: Session Initiation Protocol A Peer-to-Peer VOIP Network
SIP Network Elements
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User Agents: A software program installed in a user’s terminal or an IP phone to initiate and terminate phone calls, plus data and video communications. There are two logic parts in the user agents: User Agent Server (UAS) and User Agent Client (UAC). UAC sends requests and receives responses. UAS receives requests and sends responses. Proxy Server: Performs routing of a session invitations according to invitee's profile. There are two basic types of SIP proxy servers--stateless and stateful. Stateless servers are simple message forwarders. Stateful proxies, upon reception of a request, create a state and keep the state until the transaction finishes.Redirect Server: Receives a request and sends back a reply containing a list of the current location of a particular user, by looking up the intended recipient of the request in the location database created by a registrar.Registrar Server: A registrar is a server that accepts REGISTER requests and places the information it receives in those requests into the location service for the domain in handles.
Example SIP Call Flow IETF SIP Standards
RFC#
2974
2976
3262
3263
3265
3311
3313
3327
3329
3420
3428
3486
4028
4168
4412
4566
3261
Description
Session Announcement Protocol (SAP)
The SIP INFO Method
SIP: Session Initiation Protocol (updated by RFC 3853, RFC 4320)
Reliability of Provisional Responses in SIP
SIP: Locating SIP Servers
SIP-Specific Event Notification
SIP UPDATE Method
Private SIP Extensions for Media Authorization
SIP Extension for Registering Non-Adjacent Contacts
Security Mechanism Agreement for SIP Sessions
Internet Media Type message/sipfrag
SIP Extension for Instant Messaging
Compressing SIP
Session Timers in SIP
SCTP as a Transport for SIP
Communications Resource Priority for SIP
SDP: Session Description Protocol
SIP Phone A
RTP/RTCP stream
SIP PROXY SIP Phone B
SIP/SDP INVITESIP/SDP INVITEStatus:100 Trying
Status:183 Session Progress
Status:183 Session Progress
Status:200 OKStatus:200 OK
SIP ACKSIP ACK
SIP:BYESIP:BYE
Status:200 OKStatus:200 OK
GCPs: Gateway Control Protocols A Centralized VOIP Network
Media Gateway Control Protocol (MGCP) and H.248/MEGACO Network ElementsMedia Gateway Controller(MGC): also known as Call Agent or Softswitch, it controls a number of dumb terminals and Media Gateways. The MGC receives signaling information from MG and can instruct it to alert the called party, to send and receive voice data etc.Media Gateway(MG): acts as a translation unit between disparate telecommunications networks such as PSTN, IP Networks, Mobile access networks or PBX.Signaling Gateway (SG): A component responsible for translating signaling messages between IP network and PSTN.Endpoints: Provide audio, data and video communications with another GCP terminal or a PSTN phone via gateway.
1
2
3
4
5
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Example GCP Call Flow MGCP Documents
CallAgent
MGCPGat eway A
Endpo in t A
MGCPGat eway B
Endpo in t B
RQNTRQNT
RQNT Response
NTFY f rom A
CRCX
CRCX Response
MDCX
MDCX Response
CRCX
CRCX ResponseRinging
Answer&
RQNT Response
RTP
RTP
RTCP
NTFY f rom A
DLCX
DLCX Response DLCX Response
DLCX
VoI P
OnHook
Off Hook& Dia ll ing
Med ia Gat eway Cont ro l Pro t oco l (MGCP) Version 1 . 0
Basic MGCP Packages
MGCP Ret urn Code Usage
MGCP CAS Packages
MGCP Business Phone Packages
MGCP Red irect and Rese t Package
MGCP Lockst ep St a t e Report ing Mechan ism
Med ia Gat eway Cont ro l Pro t oco l Arch it ect u re and Requ irement s
RFC 3435
RFC 3660
RFC 3661
RFC 3064
RFC 3149
RFC 3991
RFC 3992
RFC 2805
Standard# Descri pti on
H.248/Megaco Standards Main difference between Megaco/MGCP
H.248/Megaco version 1
H.248/Megaco Version 2
H.248/Megaco Version 3
H.248.1v1
H.248.1v2
H.248.1v3
RFC 3525
RFC 3054
Gateway Control Protocol Version 1
Megaco IP Phone Media Gateway Applicat ion Prof ile
Standard ITU-T File IETF File Description Megaco/H.248
A call is represented by teminat ions within a call context
Call types include any combinat ion of mult imedia and conferencing
Syntax is text binary
Transport layer is TCP or UDP
Defined by the IETF and ITU
A call is represented by endpoints within connect ions
Call types include point-to-point and mult ipoint
Syntax is text
Transport layer is UDP
Defined by Cisco and circulated in IETF
MGCP
VOIP Media Transport Protocols
Real-Time Transport Protocol (RTP)
Real Time Control Protocol (RTCP)
Real Time Streaming Protocol (RTSP)
Reliable User Datagram Protocol (RUDP)
Secure Real-t ime Transport Protocol (SRTP)
Stream Control Transmission Protocol (SCTP)
ZRTP
For delivering audio and video over the Internet.
Provides out-of-band control information for an RTP f low.
For use in streaming media systems which allows a client to remotely control a streaming media server and allowing t ime-based access to f iles on a server.
Used as the transport protocol for MGCP based network.
Provides encrypt ion, message authent icat ion and integrity, and replay protect ion to the RTP data in both unicast and mult icast applicat ions.
Provides transport services to ensure reliable, in-sequence transport of messages with congest ion control.
An extension to RTP which describes a method of Diff ie-Hellman key agreement for SRTP.
RFC 3550
RFC 3550
RFC 2326
RFC 1151
RFC 3711
RFC 2960
Draft
Functions Standard#Protocol Name
Class-Based Weigh t ed Fa ir Queu ing (CB-WFQ)
Cust om Queu ing (CQ)
Fa ir Queu ing (FQ)
Prio r it y Queu ing(PQ)
Prio r it y Queu ing - Class-Based Weigh t ed Fa ir Queu ing
Weigh t ed Fa ir Queu ing (WFQ)
Weigh t ed Random Early Drop / Det ect (WRED)
Type o f Service (ToS)
Diff Serv
I n t Serv
Po licy-based Rout ing
Resource Reserva t ion Pro t oco l (RSVP)
Commit t ed Access Rat e (CAR)
Generic Tra ff ic Shap ing(GTS)
Mult i-Class Mu lt i l ink Po in t - t o -Po in t Pro t oco l (MCML PPP)
Frame Re lay Forum 12 (FRF. 12)
Maximum Transmission Un it (MTU)
Compressed Rea l Time Transport Pro t oco l (cRTP)
Random early de t ect ion o r Random early d iscard (RED)
CategoryQueuing
Packet Classification
Traffic shaping and policing
Fragmentation
Other
Technology
WMV Windows Media Video
Also known as H. 264 o r AVC, i t is used f o r in t e rne t , b roadcast , and on st o rage med ia .
H. 261
H. 263
H. 264
MPEG-4 Part 2
MPEG-4 Part 10
DivX
X264
I TU-T version o f MPEG-4 Part 10
MPEG
MPEG
Based on MPEG-4 Part 2
Microso f t
Based on H. 264 ; GPL
Used p r imarily in o lder video con f e rencing and video t e lephony p roduct s.
Used p r imarily f o r videocon f e rencing , video t e lephony, and in t e rne t video .
Also known as MPEG-4 Part 10 , o r AVC (f o r Advanced Video Cod ing).
Used f o r in t e rne t , b roadcast , and on st o rage med ia .
Used f o r in t e rne t , b roadcast , and on st o rage med ia .
I t can do anyt h ing f rom low reso lu t ion video f o r d ia l up in t e rne t users t o HDTV.
A GPL-l icensed imp lement a t ion o f H. 264 encod ing st andard .
I TU-T
I TU-T
,
5 - , 4 - , 3 - and 2
G. 711
G. 721
G. 722
G. 722 . 1
G. 722 . 2
G. 723
G. 723 . 1
G. 726G. 727G. 728G. 729
Speex
iLBC (Internet Low Bitrate Vocoder)
L16
U-law (US, Japan) and A-law (Europe) compand ing .
Rep laced by G. 726 .
Subband-codec t ha t d ivides 16 kHz band in t o t wo subbands, each codedusing ADPCM.
Superceded by G. 726 ; Th is is a comple t e ly d iff e ren t codec t han G. 723 . 1
Part o f H. 324 video con f e rencing .
Rep laces G. 721 and G. 723 . Re la t ed t o G. 726 .
VOI P App lica t ions.
VOI P
VOI P
AMR-WB is st andard ized f o r usage in ne t works such as UMTS.
I TU-T
I TU-T
I TU-T
I TU-T
I TU-T
I TU-T
I TU-T
I TU-TI TU-TI TU-T
Freeware
I ETF RFC 3951Freeware
I ETF RFC 3551
PCM
ADPCM
ADPCM
Transf o rm-based
AMR-WB
DPCM
MPC-MLQ or ACELP
ADPCMADPCMLDCELPCS-ACELP
CELP
LPC
LPC
Uncompressed audio data samples
64
32
64
24/ 326.60, 8.85, 12.65, 14.25,15.85, 18.25, 19.85, 23.05 and 23.85
24 / 40
5 . 6 / 6 . 3
16 / 24 / 32 / 40
168
8, 16 , 32
8 , 16
8 , 16
128
8
8
16
16
16
8
8
888
2.15-24.6 (NB)
4-44.2 (WB)
13 . 3
15 . 2
Variab le
0 . 125
Sampling
Sampling
20
Sampling
Sampling
30
0. 125Sampling0 . 62510
30 ( NB ) 34 ( WB )30
20
Sampling
0 . 75
40
30
30
1
0. 62515
30 34–
30
20
4. 1
3 . 7 -3 . 9
3 . 9
3 . 63 . 9
4 . 0
4 . 0
Codec Type
Standard by
Modulation method
Bit rate (kb/s)
Sampling rate (kHz)
Frame size (ms)
Compression delay
Mean Opinion Score (MOS) Notes
Audio CODECs
CODEC Name ApplicationsStandard
by
Video CODECsVOIP CODECsQoS Technologies
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VOIP GlossaryACELP--Algebraic Code Excited Linear PredictionADPCM--Adaptive Differential Pulse Code Modulation AMR-WB--Adaptive Multi Rate – WideBand ATA--Analog Telephone Adaptor connects the conventional telephone to the Internet, converts the analog voice signals into IP packets, delivers dial tone and manages the call setup.Broadband--High speed Internet connection, such as cable TV, DSL or dedicated telecom lines(T1/E1).C7--Common Channel Signaling 7.Cable modem--A device used to connect a computer to the high speed coaxial cable run by cable TV companies to provide access to the Internet.CALEA--Communications Assistance for Law Enforcement Act.Call agent--The intelligent and controlling entity in an MCGP based IP telephony network.Call flow--The setup and tear down process and steps for a call to start till finish.CB-WFQ--Class-Based Weighted Fair Queuing.CDR--Call Detail Record.CID--Caller Identification (ID).Circuit switched network--The traditional telephone network used for making phone calls since 1878.Codec--Compressor-Decompressor or enCOder/DECoder process.Committed Access Rate (CAR)--A QoS feature.Compression--The squeezing of data in a format that takes less space to store or less bandwidth to transmit.Compression delay--The delay caused by the compression of data.Congestion--The situation in which the traffic present on the network exceeds available network bandwidth/capacity.CoS--Class of Service.CPE--Customer Premises Equipment.cRTP--Compressed Real Time Transport Protocol.CS-ACLEP--Conjugate-Structure Algebraic-Code-Excited Linear-Prediction. Custom Queuing-- A queuing method that allows a customer to reserve a percentage of bandwidth for specified protocols. Data compression-- The process to compress large data files into small files so that they use less bandwidth during transmission and less disk space when stored.Decompression--Process by which the full data content of a compressed file is restored.DiffServ-- An architecture for implementing scalable service differentiation in the Internet for QoS.DivX-- A video codec used for internet, broadcast, and on storage media.DPCM--Differential Pulse Code Modulation. DSL modem-- A device used to connect computers to the DSL line provided by a DSL operator to gain access to the Internet.DTMF--Dual-Tone Multi Frequency.Dynamic Jitter Buffer-- Collects voice packets, stores them, and shifts them to the voice processor in evenly spaced intervals to reduce any distortion in the sound.E&M (Ear and Mouth)--A type of supervisory line signaling. E911--Enhanced 911; used for providing emergency service on cellular and Internet voice calls.Emergency 911 calls--An emergency telephone number that handles all calls related to police, fire or medical emergencies in North America.Fair Queuing--A scheduling scheme to allow several data flows to fairly share the link capacity.FoIP--Fax over Internet Protocol.Frame Relay Forum 12 (FRF.12)--A Frame Relay specification of fragmenting Frame Relay frames into smaller frames.G.711--ITU-T specification of audio CODEC. G.721--ITU-T specification of audio CODEC.G.722--ITU-T specification of audio CODEC. G.722.1--ITU-T specification of audio CODEC.G.722.2--ITU-T specification of audio CODEC. G.723--ITU-T specification of audio CODEC.G.723.1--ITU-T specification of audio CODEC. G.726--ITU-T specification of audio CODEC.G.727--ITU-T specification of audio CODEC. G.728--ITU-T specification of audio CODEC.G.729--ITU-T specification of audio CODEC.Gatekeeper--A device that translates network addresses and aliases to make connections via the H.323 protocol on a packet-switched network.Gateway--A device that acts as an interface between two or more networks to connect dissimilar communications systems.Generic Traffic Shaping (GTS)--A mechanism to control the traffic flow on a particular interface.H.225.0--A protocol for call signaling, the media (audio and video), the stream packetization, media stream synchronization and control message formats.H.235--For security in H.323 network.H.239--For dual stream use in videoconferencing.H.245--A control protocol for multimedia communication.H.246--ITU-T specification for H.323/PSTN Interworking.H.248--ITU-T standard for a centralized VOIP network. (Same as Megaco defined by IETF.)H.261--Used primarily in older videoconferencing and video telephony products.H.263--Used primarily for videoconferencing, video telephony, and internet video.H.264--Also known as MPEG-4 Part 10, or AVC (for Advanced Video Coding).H.323--An umbrella recommendation from the ITU-T that defines the protocols to provide audio-visual communication sessions on any packet network.H.350--Directory Services Architecture for Multimedia Conferencing.H.360--An architecture for end-to-end QoS control and signaling.H.450--For supplementary services such as call waiting, call forwarding, etc.H.460.x--Supplements in H.323.H.501--Protocol for mobility management and intra/inter-domain communication in multimedia systems.H.510--Mobility for H.323 multimedia systems.Hairpin--To send a call back in the direction that it came from.Hop off--Point at which a call transitions from H.323 to non-H.323, typically at a gateway.iLBC--Internet Low Bitrate Vocoder.Instant Messenging (IM)--A software that allows users to exchange messages in real time. For example, MSN Messenger, Yahoo! Messenger, etc.Internet telephony--Technologies and services of using the Internet for voice and multimedia communications.IntServ--An architecture which specifies the elements to guarantee quality of service (QoS) on networks.IP--Inernet Protocol.IP Centrex--Using IP-based network to provide centrex services such as call hold, call transfer, last number look-up and redial, call forward, three-way calling.IP fragmentation--IP datagrams to be fragmented into pieces small enough to pass over a link with a smaller MTU than the original datagram size.IP PBX--IP Private Branch Exchange. A telephone, data and video switching system, usually located on customer premises and belonging to the user.IP phone--A device that converts voice into digital packets and vice versa to make phone calls over Internet possible.IP telephony--Technologies and services for the two-way transmission of voice over IP network.IPDC--IP Device Control (protocol).IPDR--Internet Protocol Detail Record (protocol).ISDN--Integrated Services Digital Network.ITSP--Internet Telephony Service Provider.Jitter--A momentary fluctuation in the transmission signal.Lag--The extra time taken by a packet of data to travel from the source computer to the destination computer and back again.Latency--The time that elapses between the initiation of a request for data and the start of the actual data transfer.LDCELP--Low-Delay Code Excited Linear Prediction.LPC--Linear-Predictive Codec. LPCP--Lightweight Phone Control Protocol.MCML PPP--Multi-Class Multilink Point-to-Point Protocol.Media gateway (MG)--A translation unit between disparate telecommunications networks.Media gateway controller (MGC)--A system used in MGCP/H.248/Megaco VoIP telephony architectures to control a number of Media Gateways.Megaco--A IETF VOIP signaling protocol, same as H.248 of ITU-T.MGCP--Media Gateway Control Protocol.
Modulation--To carring information on a signal by varying one or more of the signal's basic characteristics -- frequency, amplitude and phase.MoIP--Modem over IP.MOS--Mean Opinion Score, a numerical indication of the perceived quality of received media after compression and/or transmission.MPEG-4 Part 10--Also known as H.264 or AVC, a video codec used for internet, broadcast, and on storage media.MPEG-4 Part 2--Used for internet, broadcast, and on storage media.MP-MLQ--Multi-Pulse, Multi-Level Quantization. MTU--Maximum Transmission Unit.NCS--Network-Based Call Signaling.Net Phone --A net phone uses the Voice over IP technology to make voice calls.Network convergence--The integration of all traffic types - voice, data and video solutions - onto a single IP network.NGN--Next Generation Network.OSP--Open Settlement Protocol.Packet loss--The loss of data packets during transmission over a computer network.Packet switched network--Networks that break messages into small packets, and route them across different channels to their destination where they are reassembled in their proper sequence.PBX--Private Branch Exchange is an in-house telephone switching system.PCM--Pulse Code Modulation.Peer-to-Peer (P2P)--A form of computing where two or more than two users can communicate directly without a central control point.Policy-based Routing--A technique used to make routing decisions based on policies set by the network administrator.POTS--Plain Old Telephone Service.PQ-CBWFQ--Priority Queuing - Class-Based Weighted Fair Queuing.PRI--Primary Rate Interface, a type of ISDN interface.Priority Queuing (PQ)--A queuing technique to give mission-critical traffic higher priority that less critical traffic.Processor drain--A drop in the quality of VoIP phone service when a user opens several applications on his computer simultaneously.Propogation delay--The time required for a signal to travel from one point to another.Proxy server-- Performs routing of a session invitations according to invitee's current location, authentication, accounting, etc.PSTN--Public Switched Telephone Network, refers to the telephone system that transmits analog voice data.Q.931--ISDN connection control protocol.QoS--Quality of Service.QSIG--Signaling standard for PBX.RADIUS--Remote Authenticaion Dial-In User Service.Random Early Detection (RED)--An active queue management algorithm. It is also a congestion avoidance algorithm.RAS--Registration, Admission, Status (RAS), a management protocol between terminals and Gatekeepers in the H.323 network.Redirect server--Receives a request and sends back a reply containing a list of the current location of a particular user.Registrar server-- Accepts REGISTER requests and places the information it receives in those requests into the location service for the domain in handles.RSVP-- Resource Reservation Protocol.RTCP-- Real Time Control Protocol.RTP-- Real Time Transport Protocol.RTSP--Real Time Streaming ProtocolRUDP--Reliable User Datagram Protocol.Sampling--A methodology used to measure the value of an analog signal at regular intervals, and encoding it into a digital format for phone services.Sampling rate--The number of samples per second taken from a continuous (analog) signal to make a discrete(digital) signal.SAP-- Session Announcement Protocol.SCCP--Skinny Client Control Protocol.SCTP--Stream Control Transmission Protocol.SDP--Session Description Protocol.Servie Level Agreement (SLA)--A contract between a network service provider and a customer that specifies what services and quality the service provider will furnish.Service provider-- A business entity that provides a communication, storage or processing service for a fee.SGCP-- Simple Gateway Control Protocol.Signaling gateway--A network component responsible for translating signaling messages between one medium (usually IP) and another (PSTN).SIGTRAN-- A family of protocols that provides reliable datagram service and user layer adaptations for SS7 and ISDN communications protocols.SIP--Session Initiation Protocol, an IP telephony signaling protocol.SIP phone-- A telephone that uses the SIP (Session Initiation Protocol) standard to make a voice call over the Internet.Skinny-- Skinny Client Control Protocol.Skype--A peer-to-peer Internet telephony company that leading the way voice calls are made by using VoIP technology.Soft switch-- A software application that is used to keep track of, monitor or regulate connections at the junction point between circuit and packet networks.Softphone-- A software application that is installed in the user’s PC enables voice calls over the Internet.Softphone client-- The software installed in the user’s computer to make calls over the Internet.Speex--A free software speech codec.SRTP--Secure Real-time Transport Protocol.SS7--Signaling System number 7.T.120-- ITU-T specifcation for Real-time Conferencing.T.38-- ITU-T specification for Facsimile over IP.TAPI--Telephony API.ToS--Type of Service.Traffic shaping--To control network traffic in order to optimize or guarantee performance, low latency, and/or bandwidthUnified Messaging (UM)-- The integration of different streams of messages (e-mail, Fax, voice, video, etc.) into a single in-box, accessible from a variety of different devices.User Agents-- A software program installed in a user’s terminal or an IP phone to initiate and terminate phone calls.V.150-- ITU-T specification for Modem over IP.Voice chat-- An application that enables two or more individuals to carry on a verbal conversation (audio conference) over the Internet.Voice over IP (VOIP)--The technology that is used to transmit voice over the Internet.Voicemail-- A telephone messaging system that digitizes the analog voice signals and stores them on disk or flash memory in a central computer.VOIP Gateway-- A device provides the conversion interface between the PSTN and an IP network for voice and fax calls.VOIP PBX-- Voice over Internet Protocol Private Branch eXchange.VOIP Phone-- A device that uses the IP network to route voice calls by converting the voice data into IP packets and vice versa.VOIP services-- Services that use the IP network to move voice data.Web phone-- A device that allows users to make voice calls over the Internet.WFQ-- Weighted Fair Queuing, a packet scheduling technique allowing guaranteed bandwidth services. WiFi phone-- A device that enables users to make phone calls from WiFi network environments.WMV-- Windows Media Video. WRED--Weighted Random Early Drop/Detect.X264-- A GPL-licensed implementation of H.264 encoding standard.ZRTP-- An extension to RTP which describes a method of Diffie-Hellman key agreement for SRTP.
Network DictionaryNetwork Protocols Handbook Network Protocol Map Network Security Map Nerwork Management Map Wireless Technology Map
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