1. TBE 2710
Chapter 12
Signaling

2. Signaling Functions Switch to switch communication
Switch to station communication
Supervising
Addressing
Alerting
Call Progress

3. Signaling Methods: In Band...
Loop-Start Signaling
Ground-Start Signaling
Wink Start

4. General Call-State Model: In-Band

5. Signaling Methods: Out-of-Band or Clear Channel...
ISDN – Primary Rate Interface (PRI)
Used for PBX and Business customers
Added features (CLID, RLT, etc.)
Quicker call setup than in-band
System Signaling No. 7 (SS7)
Used for PSTN Carrier Networks
Enables multiple network services

6. Signaling System 7 Standard Method for Linking Central Offices
Supports CLASS Services
Required for:
Local Number Portability (LNP)
E800 services
Calling Name/Number Delivery (CNAM)
Advanced Intelligent Networking (AIN)

7. Architecture of SS-7 SCP SP STP STP SP SP User SP STP STP User SP SP
SP=Signal Point
STP=Signal Transfer Point
SCP=Service Control Point

8. Purposes of SS7 Improves Call Management Enhances Network Management
Separates Network Control From Hardware
Supports User Database
Handles Addressing And Supervision
Supports 800 Number Portability
Supports Local Number Portability

9. SS7 Vs OSI

10. SS7 Messaging ISDN User Part – (ISUP)
Call Setup Messages
IAM, ACK, DIS, etc…
Transaction Capability User Part (TCAP)
Transports INAP messages
SCP Database queries
E800, LNP, CNAM, etc.

11. SS7 Signaling Examples Call Setup CNUM/CNAM E800 LNP
Global Title Translation
Point Code
CNUM/CNAM
E800
LNP

12. IP Signaling IP traffic and PSTN traffic merging
Gateways required for conversion
Protocols
H.323
Media Gateway Control (Megaco)
SIP

13. H.323
Large, open, flexible protocol with many options (good/bad), somewhat proprietary though
H.225 – call control
Session master/slave
H.245 – multimedia control
Negotiates capabilities of endpoints (intelligent or dumb).
Gatekeeper
RAS – registration, admission, status
Uses Q.931 messages (PSTN) over TCP/IP
Can be setup as peer to peer with intelligent endpoints

14. Media Gateway Control Megaco and H.248
Controls interaction between Media Gateway and Media Gateway Controller (softswitch, ie. Gatekeeper in H.323)
Call Control in central controller

15. SIP Simple protocol for multimedia applications over IP
Text messaging between endpoints
Addresses are a URL
Decentralized – intelligent endpoints
Presence
Servers keep track of users status and availability, and where to be reached (Instant Messaging uses SIP)
Proxy server – routes information, locates users and stores their preferences
Uses other protocols
SAP, SDP, TRIP, RSVP, AAA

16. SIP Advantages Operates over Any Network
Provides Expanded User Choices
Enables Developers to Create New Applications
Supports Multimedia
Allows User to Specify Best Way to Communicate

17. SIP Architecture

18. SIP Call Setup