1. Media Gateway Control Protocol
Introduction
Media gateway Control Interface
Entity Naming (Endpoint, Call, Connection, CA)
Digit Maps
Events
Commands
Protocol Description
Call Flow for RGW to TGW
Usage of Commands

2. Introduction Components Internet SS7 Network MGCP MGCP RTP SCP
Signaling
(SS7)
Gateway
SIGTRAN
Call
Agent
STP
MGCP
MGCP
Trunking
Gateway
Residential
Gateway
Trunking
Gateway
Residential
Gateway CO
Switch
Trunking
Gateway
Residential
Gateway
RTP

3. Introduction Types of Media Gateway Concept of Call Agent
Trunking Gateway to CO/Switches
Residential Gateway to PSTN Phones
Access Gateway
Business Gateway
Concept of Call Agent
call control intelligent outside gateways
master/slave
undefined CA to CA: maybe H.323, SIP+

4. Introduction Relation with H.323 Standards Internet Signaling (SS7)
Gateway
Internet
SS7/ISUP
SIGTRAN
Gatekeeper CO
Switch
Call
Agent
H.225/RAS
H.225/Q.931
H.245
Terminal or
Gateway
MGCP
Trunking
Gateway
RTP

5. H323, SIP & MGCP Concept H.323 , SIP Problems MGCP peer-to-peer
internet oriented
intelligent endpoint
optional GK
decentralized
Problems
maintenance
cost & scalability of large systems
signaling & media control are coupled
interoperability with SS7
MGCP
client-server
traditional telephony
intelligent server
“dumb” terminal
centralized
Concept
gateway decomposed
separate call control from media ports
CA, MG, SG
interoperability with PSTN

6. Media gateway Control Interface
Endpoints
Types
Digital Channel
Analog line
IVR endpoint
Naming: GW’s Domain Name + Local Name
Local Name
physical interface name / circuit number
e.g., galant.ccl.itri.org.tw/X35V3+A4/15
Wild-carded
e.g., galant.ccl.itri.org.tw/X35V3+A4/*
e.g., galant.ccl.itri.org.tw/X35V3+A4/$
(Channel)
DS0 endpoint
Analog endpoint
(Line)
(Connections)
IVR endpoint

7. Media gateway Control Interface
Calls & Connections & Call Agents
Call Identifier (Call ID)
Created by CA
Unique in the Whole System
Connection ID
Created by GW
Unique under Its GW
Usage of a Connection ID on the same EP
Waiting Period at least 3 minutes
CA Identifier (its domain name)
Redundant CAs : reliability
CA & GW keep “time-to-live” record they read from DNS

8. Media gateway Control Interface
Digit Map
CA ask GW to collect user dialed digits
Created by CA
Sent to Gateways
Usage
Gateways detect digits, letters, or timer
e.g., (11x|080xxxxxx|03xxxxxxx|002x.T)
Match accumulated digits
under-qualified, do nothing further
matched, send the collected digits to CA
over-qualified, send the digits to CA
Inter-digit Timer

9. Media gateway Control Interface
Events
package name(o) / event name
package:
Generic Media (G)
DTMF (D)
MF (M)
Trunk (T)
Line (L)
Handset (H)
RTP (R)
Network Access Server (N)
Announcement Server (A)
Script
Gateway
Supported packages
Trunk GW (ISUP)
Trunk GW (MF)
Network Access Server
Combined NAS/VOIP GW
Access GW (VOIP)
Access GW (VOIP + NAS)
Residential GW
Announcement GW
G, D, T, R
G, M, D, T, R
G, M, T, N
G, M, D, T, N, R
G, M, D, R
G, M, D, N, R
G, D, L, R
A, R

10. Media Gateway Control Interface
Commands
9 commands to handle Connection/Endpoints
EndpointConfiguration (coding charateristics)
NotificationRequest (requested events)
Notify (GW : detected events)
CreateConnection
ModifyConnection
DeleteConnection (GW also)
AuditEndpoint (query status)
AuditConnection (query status)
RestartInProgress (GW : taken in/out of service)
All commands are acknowledged.
EPCF
RQNT
NTFY
CRCX
MDCX
DLCX
AUEP
AUCX
RSIP

11. Protocol Description Transactions (simple text format) command header
a command line (case insensitive)
Action + TransId + Endpoint + Version
RQNT 1201 MGCP 1.0
a set of parameter lines
parameter name (upper case): value
X: B1 (RequestIdentifier)
R: hd (requestedEvent: hang down)
S: rg (signalRequest: ring tone)
session description

12. Protocol Description Transactions response header a response line
Response code + TransId + Commentary OK
a set of parameter lines (optional)
after CreateCX(/MDCX/DLCX/Audit/Restart)
I: A3C47F F0 (ConnectionId)
session description
Session Description Protocol
separated from header by an empty line

13. Call Flow for RGW to TGW

14. Call Flow for RGW to TGW

15. Call Flow for RGW to TGW RQNT(1) : NotificationRequest ACK to RQNT(1)
RQNT 1201 MGCP 1.0 N:
X: AC
R: hd(E(R(hu(N)),S(dl),D/(D)))
D: (11x|080xxxxxx|57xxxxx|002x.T)
ACK to RQNT(1) OK
N: NotifyEntity
X: RequestIdentifier
R: RequestEvents
D: DigitMap
E: Embedded(enable) Request
R: Notification Request
N: Notify immediately
S: Signal Request
D: Digit Map

16. Call Flow for RGW to TGW NTFY(2) : Notify from RGW ACK to NTFY(2)
NTFY 2002 MGCP 1.0 N:
X: AC O:
ACK to NTFY(2) OK
N: NotifyEntity
X: RequestIdentifier
O: ObservedEvent

17. Call Flow for RGW to TGW CRCX(3) : CreateConnection ACK to CRCX(3)
CRCX 1204 MGCP 1.0
C: A3C47F F0
L: p:10, a: G.711; G
M: recvonly
X: AD
R: hu
ACK to CRCX(3) OK
I: FDE234C8
Session Description
C: CallId
L: LocalCXOptions
p: packetize period(ms)
a: Compression Algo.
M: Mode
X: RequestIdentifier
R: RequestEvents
I: ConnectionId

18. Call Flow for RGW to TGW CRCX(4) : CreateConnection ACK to CRCX(4)
CRCX 1205 MGCP 1.0
C: A3C47F F0
L: p:10, a: G.711; G
M: sendrecv
Session Description from ACK(3)
ACK to CRCX(4) OK
I: 32F345E2
Session Description
C: CallId
M: Mode
I: ConnectionId

19. Call Flow for RGW to TGW MDCX(5) : ModifyConnection ACK to MDCX(5)
MDCX 1206 MGCP 1.0
C: A3C47F F0
I: FDE234C8
M: recvonly
Session Description from ACK(4)
ACK to MDCX(5) OK
C: CallId
I: ConnectionId
M: Mode

20. Call Flow for RGW to TGW RQNT(6) : NotificationRequest ACK to RQNT(6)
RQNT 1207 MGCP 1.0 N:
X: AE
R: hu
S: v (alerting)
ACK to RQNT(6) OK
N: NotifyEntity
X: RequestIdentifier
R: RequestEvents
S: SignalRequests

21. Call Flow for RGW to TGW MDCX(7) : ModifyConnection ACK to MDCX(7)
MDCX 1209 MGCP 1.0
C: A3C47F F0
I: FDE234C8
M: sendrecv
X: AF
R: hu
ACK to MDCX(7) OK
C: CallId
I: ConnectionId
M: Mode

22. Call Flow for RGW to TGW DLCX(8) : DeleteConnection ACK to DLCX(8)
DLCX 1210 MGCP 1.0
C: A3C47F F0
I: FDE234C8
ACK to DLCX(8) OK
P: PS=1245, OS=62345, PR=780, OR=45123, PL=10, JI=27, LA=48
C: CallId
I: ConnectionId
PS: Packets sent
OS: Octets sent
PR: Packets received
OR: Octets received
PL: Packets lost
JI: Average Jitter (ms)
LA: Average Latency (ms)

23. Usage of Commands NotificationRequest() EndpointId, [NotifiedEntity,]
[RequestedEvents,]
RequestIdentifier,
[DigitMap,]
[SignalRequests,]
[QuarantineHandling,]
[DetectEvents,]
[encapsulated EndpointConfiguration]
Request
Notify
Request
Time
Quarantine Period Q T
Q: process/discard
step/loop (notify)
T: events to detect
during quarantine

24. Usage of Commands CreateConnection() CallId, EndpointId,
[NotifiedEntity,]
[LocalConnectionOptiona,]
Mode,
[{RemoteConnectDescptr|SecondEndpointId}]
[EncapsulatedNotificationRequest,]
[encapsulated EndpointConfiguration]
Hairpin Connection

25. Usage of Commands DeleteConnection()
Delete one connection from Call Agent
ConnectionId in the parameter line
GW : Connection parameters
Multiple connection from Call agent
only EndpontId (and CallId) in the parameter line
GW: No connection parameter
From gateway
Reason-Code & Connection-Parameters in Command

26. MGCP Applications (1) IP Switch IP Networks Call Agent PSTN Switch
IP PBX
IP Networks
SS7
SGW
SGW
SS7
Call Agent
TGW
TGW

27. MGCP Applications (2) IP PBX IP Networks Call Agent PSTN PBX IP PBX
SGW
SS7
TGW
Call Agent
TGW