? isup is used in pstn, isdn, msc/gmsc of gsm and the ... · 14 s-38.130 telecom technology...
TRANSCRIPT
1 S-38.130 Telecom Technology
The Interworking of IP Telephony with Legacy Networks
? ISUP is used in PSTN, ISDN, MSC/GMSC of GSM and the gateway of
IS-41.
–ISUP is the 'almighty' signaling for inter-connecting the different
telephony networks
• In IP Telephony networks, the signaling is SIP, H.323 or
MGCP/MEGACO.
• The signaling of Interworking:
–1, SIP-ISUP
–2, H.323-ISUP
–3, MGCP/MEGACO-ISUP(also TCAP)
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SIP-ISUP
• SIP overview:
– SIP URLs– Format= User@host
– examples:
• [email protected]• [email protected]
– Locating a SIP Server: Client request( E.g. INVITE) is sent to SIP server– Either default local proxy SIP server
– Or SIP server for called party
3 S-38.130 Telecom Technology
SIP-ISUP
• PSTN? IP ? PSTN
–PSTN1 calls MGC1
The signaling is the ISUP
–MGC1 calls MGC2
The signaling is the SIP
–MGC2 calls PSTN2
The signaling is the ISUP
• SIP looks like a transparent media for ISUP.
MGC2 MGC1
VoIP Network
PROXY
SS7/C7
PROXY
SS7/C7
PSTN2PSTN1
4 S-38.130 Telecom Technology
SIP-IP
• PSTN? IP ? PSTN
Call flow:
IAM
M G C # 2M G C # 1 P R O X Y
INVITE
P S T N
1 0 0 T R Y I N G
IAM
P S T N
A C M1 8 3 S E S S I O NPro
A C M
A N M
2 0 0 O K
A N M
A C K
Conversat ion
REL
B Y E
R E L
R L C
2 0 0 O K
R L C
5 S-38.130 Telecom Technology
SIP-ISUP
• PSTN ? IP
–PSTN calls the MGC
The signaling is ISUP
– MGC calls the SIP server and SIP phone
The signaling is SIP
Note:
– The SIP phone should already register to a SIP server.
– SIP server could be a proxy or a redirect server
MGC
VoIP Network
SIP server
PROXY
SS7/C7
SIPphone
PSTN
6 S-38.130 Telecom Technology
SIP-IP
• PSTN ? IP
Call Flow:
IAM
M G C P R O X Y
I N V I T E
P S T N
1 0 0 T R Y I N G
SIP-phone
1 8 0R I N G I N G
1 8 0 R I N G I N G
A C M
2 0 0 O K
A N M
A C K
Conversa t ion
R E L
B Y E
B Y E
2 0 0 O K
R L C
I N V I T E
2 0 0 O K
A C K
2 0 0 O K
7 S-38.130 Telecom Technology
SIP-ISUP
• IP ? PSTN
–SIP phone calls the MGC
The signaling is SIP
–MGC calls the PSTN
The signaling is ISUP
MGC
VoIP Network
PROXY
SS7/C7
SIP server
PSTNSIPphone
8 S-38.130 Telecom Technology
SIP-IP
• IP ? PSTN IAM
M G CPROXY
INVITE
PSTN
100 TRYING
SIP-phone
ACM
183 SESSION
183Sess ion
2 0 0 O K
ANM
ACK
Conversat ion
R E L
BYE
B Y E
2 0 0 O K
R L C
INVITE
2 0 0 O K
A C K
BYE
9 S-38.130 Telecom Technology
H.323-ISUP
H.323:
–H.225.0: Call Signaling and media packetisation
Specifies call setup message which are based on Q.931
–H.245: Call control
MGC:
–Map the ISUP signaling to H.225 signaling and H.225 signaling to ISUP for call setup.
–Map the ISUP signaling to H.245 signaling and H.245 signaling to ISUP for call control.
10 S-38.130 Telecom Technology
H.323-ISUP
• Q.931 channel
–Carries call setup messages to set up H.245
–Can be closed as soon as H.245 Channel set up
H.245 Channel
Q.931 Channel
MGC MGC
• H.245 channel
–Exchange audio/video capabilities
–Master/slave determination
–initiate setup of RTP sessions
–Terminate call
11 S-38.130 Telecom Technology
MGCP/MEGACO-ISUP
• Gateway Decomposition
–Scalability
–Seamless PSTN Integration
–SS7/C7 connectivity
–Availability
• 2 kind of Gateway
–Trunk(TGW)
Connects PSTN to IP network
–Residential(RGW)
Connects residential telephone an IP network
12 S-38.130 Telecom Technology
MGCP/MEGACO-ISUP
• Call agent
–Controls TGW and RGW using MGCP/MEGACO
–Handles SS7/C7 signaling for trunks that interconnect PSTN with IP network
–Interacts with SCPs over SS7 networking support of various services
–May support SIP/H.323 signaling
• In UMTS All-IP Core Network, the Call agent is ' CallProcessing Server' (CPS)
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MGCP/MEGACO-ISUP
Here is a example of MGCP-ISUP
MGCP/MEGACO also support the mapping of TCAP
RGW
TGW
Internet
Call agent
RGW
Call Agent
SS7GW
PSTN
SS7/TCAP,SS7/ISUP
STP
SCP
MGCP
MGCP
MGCP
Signal
Voice
14 S-38.130 Telecom Technology
MGCP/MEGACO-ISUP
Call Flow of the MGCP-ISUP C:Providedialtone andcollect digits
TGW
Call agent
Off-hook
SS7
I:Off-hook
Caller
C:Createconnection
I:Digits dialled
Dial toneDigits
C:CreateConnectionsending to RGW IPaddress, UDP port
RTP voice packets
A C M
Ringing from PSTN
IAM
ANM
RGW
I: RGW IPaddress,UDP Port
A C M
I: TGW IPaddress,UDP Port
C:ModifyConnection to sendto TGW IP address,UDP por t
15 S-38.130 Telecom Technology
UMTS All-IP Core Network
BSS
IP Network
HSS
GPRSHLR
UMS
CPS
CSCF
MGCF
GW
T-SGW
R-SGW
MGW
MRF
SGSN
Here is The UMTS All-IP Core Network .
In UMTS All-IP Core Network , R-SGW is used for the MAP connection to the Legacy 2G Network for Roaming.