ETSI TS 103 161-4 V1.1.1 (2011-10)

Technical Specification
Access, Terminals, Transmission and Multiplexing (ATTM);
Integrated Broadband Cable and Television Networks;
IPCablecom 1.5;
Part 4: Network Call Signalling Protocol

2 ETSI TS 103 161-4 V1.1.1 (2011-10)

Reference
DTS/ATTM-003011-4
Keywords
access, broadband, cable, multimedia, PSTN
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ETSI
3 ETSI TS 103 161-4 V1.1.1 (2011-10)
Contents
Intellectual Property Rights . 6
Foreword . 6
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 9
3 Definitions and abbreviations . 10
3.1 Definitions . 10
3.2 Abbreviations . 11
4 Void . 12
5 Technical Overview . 12
6 Introduction . 14
6.1 Relation With H.323 Standards . 14
6.2 Relation With IETF Standards . 15
6.3 Relation to RFC 3435 and ABNF Grammar . 16
7 Media Gateway Control Interface (MGCI) . 16
7.1 Model and Naming Conventions . 16
7.1.1 Endpoint Names . 16
7.1.1.1 Embedded Client Endpoint Names . 17
7.1.1.1.1 Analog Access Line Endpoints . 18
7.1.1.1.2 Video Endpoints . 18
7.1.2 Call Names. 18
7.1.3 Connection Names . 18
7.1.4 Names of Call Agents and Other Entities . 19
7.1.5 Digit Maps . 19
7.1.6 Events and Signals . 21
7.2 SDP Use . 23
7.3 Gateway Control Functions . 23
7.3.1 NotificationRequest . 25
7.3.2 Notifications . 30
7.3.3 CreateConnection . 31
7.3.4 ModifyConnection . 36
7.3.5 DeleteConnection (From the Call Agent) . 38
7.3.6 DeleteConnection (From the Embedded Client) . 39
7.3.7 DeleteConnection (Multiple Connections From the Call Age nt) . 40
7.3.8 Auditing . 40
7.3.8.1 AuditEndPoint . 41
7.3.8.2 AuditConnection . 43
7.3.9 Restart in Progress . 44
7.4 States, Failover and Race Conditions . 45
7.4.1 Recaps and Highlights . 45
7.4.2 Retransmission, and Detection of Lost Associations . 46
7.4.3 Race Conditions . 49
7.4.3.1 Quarantine list . 49
7.4.3.2 Explicit Detection . 53
7.4.3.3 Transactional Semantics . 54
7.4.3.4 Ordering of Commands, and Treatment of Disorder . 54
7.4.3.5 Fighting the Restart Avalanche . 55
7.4.3.6 Disconnected Endpoints . 56
7.4.3.7 Call Agent Handling of Disconnected Endpoints . 58
7.5 Return Codes and Error Codes . 59
7.6 Reason Codes . 60
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4 ETSI TS 103 161-4 V1.1.1 (2011-10)
7.7 Use of Local Connection Options and Connection Descriptors . 61
7.7.1 RFC 2833 Negotiation . 63
7.7.2 Selecting Codec Packetization Interval for T.38. 63
7.7.3 Remote IP and Port Negotiation . 64
7.7.4 LCO Use with FXR Package . 64
7.7.5 LCO with FXR and VBD Being Used by CMS at Same Time . 65
7.7.6 LCO format for V.152 and RFC 2198 Redundancy use . 65
8 Media Gateway Control Protocol . 65
8.1 General Description . 66
8.2 Command Header . 66
8.2.1 Command Line . 66
8.2.1.1 Requested Verb Coding . 67
8.2.1.2 Transaction Identifiers . 67
8.2.1.3 Endpoint, Call Agent and NotifiedEntity Name Coding . 68
8.2.1.4 Protocol Version Coding . 68
8.2.2 Parameter Lines . 68
8.2.2.1 Response Acknowledgement . 71
8.2.2.2 RequestIdentifier . 71
8.2.2.3 Local Connection Options . 71
8.2.2.4 Capabilities. 73
8.2.2.5 Connection Parameters . 74
8.2.2.6 Reason Codes . 74
8.2.2.7 Connection Mode . 74
8.2.2.8 Event/Signal Name Coding . 75
8.2.2.9 RequestedEvents . 75
8.2.2.10 SignalRequests . 76
8.2.2.11 ObservedEvents . 77
8.2.2.12 RequestedInfo . 77
8.2.2.13 QuarantineHandling . 78
8.2.2.14 DetectEvents . 78
8.2.2.15 EventStates . 78
8.2.2.16 ResourceID. 78
8.2.2.17 RestartMethod . 78
8.2.2.18 VersionSupported . 78
8.2.2.19 MaxMGCPDatagram . 79
8.3 Response Header Formats . 79
8.3.1 CreateConnection . 81
8.3.2 ModifyConnection . 81
8.3.3 DeleteConnection . 82
8.3.4 NotificationRequest . 82
8.3.5 Notify . 82
8.3.6 AuditEndpoint . 82
8.3.7 AuditConnection . 82
8.3.8 RestartInProgress . 83
8.4 Session Description Encoding . 83
8.4.1 Use of SDP . 83
8.4.2 SDP Parameters Common to both Audio (m=audio media line) and Image (m=image media line)
Service Use . 84
8.4.2.1 Protocol Version (v=) . 84
8.4.2.2 Origin (o=) . 84
8.4.2.3 Session Name (s=) . 84
8.4.2.4 Session and Media Information (i=) . 85
8.4.2.5 URI (u=) . 85
8.4.2.6 E-Mail Address and Phone Number (e=, p=) . 85
8.4.2.7 Connection Data (c=) . 85
8.4.2.8 Bandwidth (b=) . 85
8.4.2.9 Time, Repeat Times and Time Zones (t=, r=, z=) . 86
8.4.2.10 Attributes (a=) . 86
8.4.3 SDP Audio Service Use . 87
8.4.3.1 Encryption Keys: . 87
8.4.3.2 Attributes (a=) . 88
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8.4.3.3 Media Announcements (m=) . 90
8.4.4 SDP Image Service Use for T.38 . 90
8.4.4.1 Encryption Keys: . 91
8.4.4.2 Attributes (a=) . 91
8.4.4.3 Media Announcements (m=) . 93
8.5 Transmission Over UDP . 93
8.5.1 Reliable Message Delivery . 93
8.5.2 Retransmission Strategy . 94
8.5.3 Maximum Datagram Size, Fragmentation and Reassembly . 94
8.6 Piggy-Backing . 95
8.7 Transaction Identifiers And Three Ways Handshake . 95
8.8 Provisional Responses . 96
9 Security. 97
Annex A (normative): Event Packages . 98
A.1 Analogue Access Lines . 98
A.2 Line Package . 99
A.3 FAX Package . 103
A.4 VoIP Metrics Package . 103
A.5 Vbd and GPMD packages . 104
Annex B (normative): Connection Mode . 105
Annex C (normative): Dynamic Quality-of-Service . 108
C.1 Introduction . 108
C.2 NCS/D-QoS State Machine . 109
Annex D (informative): Example Command Encodings . 115
D.1 NotificationRequest . 115
D.2 Notify . 115
D.3 CreateConnection . 116
D.4 ModifyConnection . 117
D.5 DeleteConnection (from the Call Agent) . 118
D.6 DeleteConnection (from the Embedded Client) . 118
D.7 DeleteConnection (Multiple Connections From the Call Agent) . 118
D.8 AuditEndpoint . 119
D.9 AuditConnection . 120
D.10 RestartInProgress . 120
Annex E (informative): Example Call Flow . 122
Annex F (informative): Compatibility Information . 128
F.1 MGCP Compatibility . 128
Annex G (normative): ABNF Grammar for NCS . 129
Annex H (informative): Bibliography . 137
History . 138

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6 ETSI TS 103 161-4 V1.1.1 (2011-10)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Access, Terminals, Transmission
and Multiplexing (ATTM).
The present document is part 4 of a multi-part IPCablecom 1.5 deliverable covering the Digital Broadband Cable
Access to the Public Telecommunications Network; IP Multimedia Time Critical Services, as identified below:
Part 1: "Overview";
Part 2: "Architectural framework for the delivery of time critical services over Cable Television Networks using
Cable Modems";
Part 3: "Audio Codec Requirements for the Provision of Bi-Directional Audio Service over Cable Television
Networks using Cable Modems";
Part 4: "Network Call Signalling Protocol";
Part 5: "Dynamic Quality of Service for the Provision of Real Time Services over Cable Television Networks
using Cable Modems";
Part 6: "Event Message Specification";
Part 7: "Media Terminal Adapter (MTA Management Information Base (MIB)";
Part 8: "Network Call Signalling (NCS) MIB Requirements";
Part 9: "Security";
Part 10: "Management Information Base (MIB) Framework";
Part 11: "Media terminal adapter (MTA) device provisioning";
Part 12: "Management Event Mechanism";
Part 13: "Trunking Gateway Control Protocol - MGCP option";
Part 14: "Embedded MTA Analog Interface and Powering Specification"
Part 15: "Analog Trunking for PBX Specification";
Part 16: "Signalling for Call Management Server";
Part 17: "CMS Subscriber Provisioning Specification";
Part 18: "Media Terminal Adapter Extension MIB";
Part 19: "IPCablecom Audio Server Protocol Specification - MGCP option";
Part 20: "Management Event MIB Specification";
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7 ETSI TS 103 161-4 V1.1.1 (2011-10)
Part 21: "Signalling Extension MIB Specification".
NOTE 1: Additional parts may be proposed and will be added to the list in future versions.
NOTE 2: The choice of a multi-part format for this deliverable is to facilitate maintenance and future
enhancements.
ETSI
8 ETSI TS 103 161-4 V1.1.1 (2011-10)
1 Scope
The present document specifies a profile of the Media Gateway Controller Protocol (MGCP) for IPCablecom 1.5
embedded clients. MGCP is a call signalling protocol for use in a centralized call control architecture, and assumes
relatively simple client devices. The call signalling protocol is one layer of the overall IPCablecom 1.5 suite of
documents and relies upon companion protocol documents to provide complete end-to-end IPCablecom functionality.
The present document describes an IPCablecom profile of an application programming interface (MGCI), and a
corresponding protocol (MGCP) for controlling Voice-over-IP (VoIP) embedded clients external call control elements.
The profile is referred to as the Network Call Signalling (NCS) Protocol.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] IETF RFC 3435 (January 2003): "Media Gateway Control Protocol (MGCP)" Version 1.0.
[2] IETF RFC 1890 (January 1996): "RTP Profile for Audio and Video Conferences with Minimal
Control".
[3] IETF RFC 2327 (April 1998): "Session Description Protocol (SDP)".
[4] TCP/IP Illustrated, Volume 1: "The Protocols, Stevens, W. Richard, Addison-Wesley", 1994.
[5] ETSI TS 103 161-3: "Access, Terminals, Transmission and Multiplexing (ATTM); Integrated
Broadband Cable and Television Networks; IPCablecom 1.5; Part 3: Audio Codec Requirements
for the Provision of Bi-Directional Audio Service over Cable Television Networks using Cable
Modems".
[6] ETSI TS 103 161-5: "Access, Terminals, Transmission and Multiplexing (ATTM); Integrated
Broadband Cable and Television Networks; IPCablecom 1.5 Part 5: Dynamic Quality of Service
for the Provision of Real Time Services over Cable Television Networks using Cable Modems".
[7] ETSI TS 103 161-9: "Access, Terminals, Transmission and Multiplexing (ATTM); Integrated
Broadband Cable and Television Networks; IPCablecom 1.5 Part 9: Security".
[8] IETF RFC 2231 (November 1997): "MIME Parameter Value and Encoded Word Extensions:
Character Sets, Languages, and Continuations".
[9] Telcordia GR-506: "LSSGR: Signaling for Analog Interfaces," December 1996.
[10] ITU-T Recommendation T.38: "Procedures for real-time Group 3 facsimile communication over
IP networks", March 2002.
[11] IETF RFC 2198 (September 1997): "RTP Payload for Redundant Audio Data".
[12] ITU-T Recommendation V.152: "Procedures for supporting voice-band data over IP networks",
January 2005.
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9 ETSI TS 103 161-4 V1.1.1 (2011-10)
[13] IETF RFC 5347 (October 2008): "Media Gateway Control Protocol Fax Package".
[14] IETF RFC 3660: "Basic Media Gateway Control Protocol (MGCP) Packages".
[15] IETF draft-auerbach-mgcp-rtcpxr-00: "Media Gateway Control Protocol VoIP RTCP-XR Metrics
Package".
NOTE: Available at http://docbox.etsi.org/Reference/IETF/Drafts/draft-auerbach-mgcp-rtcpxr-00.PDF.
[16] IETF draft-stone-mgcp-vbd-00: "Media Gateway Control Protocol Voiceband Data Package and
General Purpose Media Descriptor Parameter Package".
NOTE: Available at http://docbox.etsi.org/Reference/IETF/Drafts/draft-stone-mgcp-vbd-00.PDF.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] IETF RFC 1889: "RTP: A Transport Protocol for Real-Time Applications", January 1996.
[i.2] IETF RFC 2974: "SAP - Session Announcement Protocol", October 2000.
[i.3] IETF RFC 2326: "Real-time Streaming Protocol (RTSP)", April 1998.
[i.4] RTP Parameters.
NOTE: Available at http://www.Iana.org/assignments/rtp-parameters/.
[i.5] Telecordia: Notes on the Networks, SR-2275.
NOTE: Available at http://telecom-info.telcordia.com/site-cgi/ido/docs.cgi.
[i.6] IETF RFC 2821/STD0010, J. Klensin, Editor: "Simple Mail Transfer Protocol", April 2001.
[i.7] IETF RFC 1122/STD0003: "Requirements for Internet Hosts -- Communication Layers",
October 1989.
[i.8] IETF STD0013: "Domain Names - Implementations and Specifications", November 1987.
[i.9] IETF RFC 2234: "Augmented BNF for Syntax Specifications: ABNF", November 1997.
[i.10] IETF RFC 2833: "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals",
May 2000.
[i.11] ITU-T Recommendation T.30: "Procedures for Document Facsimile Transmission in the General
Switched Telephone Network", April 1999.
[i.12] ITU-T Recommendation V.8: "Procedures for Starting Sessions of Data Transmission over the
Public Switched Telephone Network", November 2000.
[i.13] ITU-T Recommendation V.21: "300 Bits Per Second Duplex Modem Standardized for Use in the
General Switched Telephone Network", November 1988.
[i.14] ITU-T Recommendation V.25: "Automatic Answering Equipment and General Procedures for
Automatic Calling Equipment on the General Switched Telephone Network Including Procedures
for Disabling of Echo Control Devices for both Manually And Automatically Established Calls",
October 1996.
[i.15] ITU-T Recommendation V.18: "Operational and interworking requirements for DCEs operating in
the text telephone mode", November 2000.
[i.16] IETF RFC 2474: "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6
Headers", December 1998.
[i.17] IETF RFC 3261: "SIP: Session Initiation Protocol", June 2002.
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10 ETSI TS 103 161-4 V1.1.1 (2011-10)
[i.18] ITU-T Recommendation H.225: "Call signalling protocols and media stream packetization for
packet-based multimedia communication systems".
[i.19] ITU-T Recommendation H.245: " Control protocol for multimedia communication".
[i.20] IETF RFC 821: "Simple Mail Transfer Protocol".
[i.21] IETF RFC 2373: "IP Version 6 Addressing Architecture".
[i.22] ITU-T Recommendation H.323: "Packet-based multimedia communications systems".
[i.23] IETF RFC 3264: "An Offer/Answer Model with Session Description Protocol (SDP)".
[i.24] IETF RFC 2045: "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies".
[i.25] Telcordia GR-586 (April 2002): "Call Forwarding Subfeatures, FSD 01-02-1450".
NOTE: Available at http://telecom-info.telcordia.com/site-cgi.
[i.26] Telcordia GR-30 (December 1998): "LSSGR Voiceband Data Transmission Interface".
NOTE: Available at http://telecom-info.telcordia.com/site-cgi/ido/docs.cgi.
[i.27] Telcordia SR-TSV-002476 (December 1992): "CPE Compatibility Considerations for the
VoicebandData Transmission-Interface".
NOTE: Available at http://telecom-info.telcordia.com/site-cgi/.
[i.28] Telcordia GR-1401 (June 2000) "Visual Message Waiting Indicator Generic Requirements (FSD
01-02-2000)".
NOTE: Available at http://telecom-info.telcordia.com/site-cgi.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
authentication: process of verifying the claimed identity of an entity to another entity
authorization: act of giving access to a service or device if one has permission to have the access
ciphersuite: set which contains both an encryption algorithm and a message authentication algorithm (e.g. a MAC or an
HMAC)
NOTE: In general, it may also contain a key-management algorithm, which does not apply in the context of
IPCablecom.
downstream: direction from the headend toward the subscriber location
encryption: method used to translate plaintext into ciphertext
encryption key: key used in a cryptographic algorithm to translate the plaintext to ciphertext
endpoint: Terminal, Gateway or Multipoint Conference Unit (MCU)
event message: message capturing a single portion of a connection
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11 ETSI TS 103 161-4 V1.1.1 (2011-10)
gateway: devices bridging between the IPCablecom IP Voice Communication world and the PSTN
NOTE: Examples are the Media Gateway, which provides the bearer circuit interfaces to the PSTN and
transcodes the media stream, and the Signalling Gateway, which sends and receives circuit switched
network signalling to the edge of the IPCablecom network.
H.323: ITU-T recommendation for transmitting and controlling audio and video information.
NOTE: The ITU-T Recommendation H.323 [i.22] requires the use of the ITU-T Recommendation H.225 [i.18]
and ITU-T Recommendation H.245 [i.19] protocol for communication control between a "gateway"
audio/video endpoint and a "gatekeeper" function.
header: protocol control information located at the beginning of a protocol data unit
integrity: way to ensure that information is not modified except by those who are authorized to do so
jitter: variability in the delay of a stream of incoming packets making up a flow such as a voice communication
key: mathematical value input into the selected cryptographic algorithm
latency: time, expressed in quantity of symbols, taken for a signal element to pass through a device
network management: functions related to the management of data across the network
plaintext: original (unencrypted) state of a message or data
NOTE: Also called cleartext.
upstream: direction from the subscriber location toward the head end
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AAD Average Acknowledgement Delay
API Application Program Interface
ATM Asynchronous Transfer Mode
AV Audio Video
BNR Backus-Naur form
CA Call Agent ®
CM DOCSIS Cable Modem
CMS Call Management Server
CMTS Cable Modem Termination System
COdec COder-DECoder
CRCX Create Connection
DNS Domain Name Service ®
DOCSIS Data-Over-Cable Service Interface Documents
DQoS Dynamic Quality-of-Service
DSA Dynamic Service Add
DSC Dynamic Service Change
DSCP DiffServ Code Point.
DTMF Dual-tone Multi Frequency (tones)
E-MTA Embedded MTA
ETSI European Telecommunications Standards Institute
IANA Internet Assigned Numbers Authority
LCO Local Connection Options
IETF Internet Engineering Task Force
IP Internet Protocol
IPsec Internet Protocol Security
ITU International Telecommunication Union
ITU-T International Telecommunication Union-Telecommunication Standardization Sector
LSSGR LATA Switching Systems Generic Requirements
MAC Media Access Control+
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12 ETSI TS 103 161-4 V1.1.1 (2011-10)
MC Multipoint Controller
MCU Multipoint Conferencing Unit
MDCX Modify Connection
MDU Multi-Dwelling Unit
MEGACO Media Gateway Control IETF working group
MF Multi-Frequency
MG Media Gateway
MGC Media Gateway Controller
MGCI Media Gateway Control Interface
MGCP Media Gateway Control Protocol
MIB Management Information Base
MTA Multimedia Terminal Adapter
MWD Maximum Waiting Delay
NCS Network Call Signalling
NTP Network Time Protocol
PBX Private Branch Exchange
PSTN Public Switched Telephone Network
QoS Quality of Service
RC4 Rivest Cipher 4
RCD Remote Connection Descriptor
RFC Request for Comments
RSVP Resource Reservation Protocol
RTCP Real-Time Control Protocol
RTSP Real-Time Streaming Protocol
RTO Retransmission Timeout
RTP Real-time Transport Protocol
SAP Session Announce Protocol
SDP Session Description Protocol
SIP Session Initiation Protocol
SNMP Simple Network Management Protocol
TCP Transmission Control Protocol
TD Timeout for Disconnect.
TOS Type of Service
UDP User Datagram Protocol
VAD Voice Activity Detection
UDPTL UDP Transport Layer
VoIP Voice-over-IP
4 Void
5 Technical Overview
The present document describes a profile of the Media Gateway Control Protocol (MGCP) for IPCablecom embedded
clients, which we will refer to as the IPCablecom Network-based Call Signalling (NCS) protocol. MGCP is a call
signalling protocol for use in a centralized call control architecture, and assumes relatively simple client devices. The
call signalling protocol is one layer of the overall IPCablecom suite of documents and relies upon companion protocol
documents to provide complete end-to-end IPCablecom functionality. The scope of NCS is currently only embedded
Voice-over-IP client devices in an IPCablecom environment and the NCS profile has therefore simplified and in some
cases modified the base MGCP 1.0 protocol accordingly. Support for video will be added in a later version of the
present document.
The present document describes an IPCablecom profile of an application programming interface (MGCI), and a
corresponding protocol (MGCP) for controlling voice-over-IP (VoIP) embedded clients from external call control
elements. The MGCP assumes a call control architecture where the call control "intelligence" is outside the gateways
and is handled by external call control elements.
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13 ETSI TS 103 161-4 V1.1.1 (2011-10)
The present document is based on the Media Gateway Control Protocol (MGCP) 1.0 RFC [1], which was the result of a
merge of the IETF draft of Simple Gateway Control Protocol, and the IETF draft of IP Device Control (IPDC) family of
protocols, as well as input generated by the IPCablecom embedded client signalling team that developed this profile.
The present document, which defines the IPCablecom NCS Protocol document, constitutes a document that is
independent of MGCP in order to provide a stable reference document, while meeting current time-to-market demands
for such a reference. It is the intent of the present document to be as closely aligned with MGCP as possible for the
IPCablecom environment, in order to avoid developing multiple protocols to solve the same problem. This goal has
been, and continues to be, pursued through cooperation with the authors of the MGCP document. The NCS profile of
MGCP, however, is strictly and solely defined by the contents of the present document.
This NCS profile of MGCP, referred to as the Network-based Call Signalling Protocol 1.0, NCS 1.0, the NCS profile, or
simply NCS in the present document, has been modified from the MGCP 1.0 RFC in the following ways:
• The NCS protocol only aims at supporting IPCablecom-embedded clients: The NCS protocol supports
embedded clients as defined by IPCablecom. Functionality present in the MGCP 1.0 protocol, which was
superfluous to NCS, has been removed.
• The NCS protocol contains extensions and modifications to MGCP: IPCablecom-specific requirements have
been addressed in NCS, which has resulted in a couple of minor extensions and modifications to MGCP.
However, the MGCP architecture, and all of the MGCP constructs relevant to embedded clients, are preserved
in NCS.
• The NCS protocol contains minor simplifications from MGCP 1.0: Where several choices were available, and
not necessarily needed for an embedded client in the IPCablecom environment, some simplifications have
been made for embedded-client implementations.
Although MGCP is not NCS, and NCS is not MGCP, the name
...