© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Identifying Voice Networking Considerations Identifying Design Considerations for Voice Services

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Separate Voice and Data Networks Companies want to reduce WAN costs by integration. Data is primary traffic on many voice networks. PSTN architecture is not flexible enough. PSTN can not integrate voice, data, and video.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Voice over IP

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: IP Telephony

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Introducing H.323 ITU-T standard Describes packet-based video, audio, and data communication across packet-based networks Provides session setup, monitoring, and termination Refers to a set of other standards: –H.225 (Q.931): Call signaling –H.245: Capability negotiation and media stream management

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v H.323 Components

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: H.323 Components and Their Interactions

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v The Importance of a Gatekeeper

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v IP Telephony Components

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Design Goals of IP Telephony To use end-to-end IP telephony between sites with IP connectivity To make IP telephony widely usable To lower long-distance costs To make IP telephony cost-effective To provide high availability of IP telephony To offer lower total cost of ownership and greater flexibility To enable new applications on top of IP telephony via third-party software To improve remote worker, agent, and work-at-home staff productivity To facilitate data and telephony network consolidation

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Single-Site IP Telephony Design

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Multisite WAN with Centralized Call Processing Design

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Multisite WAN with Distributed Call Processing Design

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Call Control and Transport Protocols Voice call control functions: –Q.931 call setup signaling –H.245 call capability control –RAS signaling –RTP Control Protocol (RTCP) Voice conversation: –Real-Time Transport Protocol (RTP)

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v SCCP Control SCCP is a client-server protocol. SCCP clients register with Cisco Unified CallManager to receive their configuration information. Media connections between SCCP clients use RTP.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v SIP Control SIP is a peer-to-peer protocol. SIP user agents communicate with SIP proxy server. SIP phones can register with Cisco Unified CallManager.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v MGCP Control MGCP is a client-server protocol. MGCP gateway translates between endpoints and IP phones. Call agents control MGCP endpoints.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Summary Business needs are driving the need for unified voice and data networks not on the PSTN. The H.323 standard is a foundation for audio, video, and data communications across IP-based networks, including the Internet. IP telephony refers to communication services and voice, facsimile, and voice-messaging applications that are transported via the IP network rather than the PSTN. Voice communication over IP relies on control protocols such as H.323, SCCP, SIP, and MGCP.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v