© 2006 Cisco Systems, Inc. All rights reserved Introducing VoIP Networks

© 2006 Cisco Systems, Inc. All rights reserved. Objectives  Describe the benefits of a VoIP network.  Describe the components of a VoIP network.  Describe the legacy analog interfaces used in VoIP networks.  Describe the digital interfaces used in VoIP networks.  Explain the 3 phases of call control.  Compare and contrast distributed and centralized call control.

© 2006 Cisco Systems, Inc. All rights reserved. Benefits of a VoIP Network  More efficient use of bandwidth and equipment  Lower transmission costs  Consolidated network expenses  Improved employee productivity through features provided by IP telephony: IP phones are complete business communication devices. Directory lookups and database applications (XML) Integration of telephony into any business application Software-based and wireless phones offer mobility.  Access to new communications devices (such as PDAs and cable set-top boxes)

© 2006 Cisco Systems, Inc. All rights reserved. Components of a VoIP Network

© 2006 Cisco Systems, Inc. All rights reserved. Legacy Analog and VoIP Applications Can Coexist

© 2006 Cisco Systems, Inc. All rights reserved. Legacy Analog Interfaces in VoIP Networks Analog Interface TypeLabelDescription Foreign Exchange StationFXSUsed by the PSTN or PBX side of an FXS–FXO connection Foreign Exchange OfficeFXOUsed by the end device side of an FXS–FXO connection Earth and MagnetoE&MTrunk, used between switches

© 2006 Cisco Systems, Inc. All rights reserved. Legacy Analog Interfaces in VoIP Networks

© 2006 Cisco Systems, Inc. All rights reserved. Digital Interfaces InterfaceVoice Channels (64 kbps Each)Signaling Framing Overhead Total Bandwidth BRI21 channel (16 kbps)48 kbps192 kbps T1 CAS24 (no clean 64 kbps because of robbed-bit signaling) in-band (robbed-bits in voice channels) 8 kbps1544 kbps T1 CCS231 channel (64 kbps)8 kbps1544 kbps E1 CAS3064 kbps 2048 kbps E1 CCS301 channel (64 kbps)64 kbps2048 kbps

© 2006 Cisco Systems, Inc. All rights reserved. Call Setup  Checks call-routing configuration  Determines bandwidth availability If bandwidth is available, setup message is passed If bandwidth is not available, busy signal is generated

© 2006 Cisco Systems, Inc. All rights reserved. Call Maintenance  Tracks quality parameters: Packet loss Jitter Delay  Maintains or drops call based on connection quality

© 2006 Cisco Systems, Inc. All rights reserved. Call Teardown  Notifies devices to free resources  Resources are made available to subsequent calls

© 2006 Cisco Systems, Inc. All rights reserved. Distributed Call Control

© 2006 Cisco Systems, Inc. All rights reserved. Centralized Call Control

© 2006 Cisco Systems, Inc. All rights reserved. Self Check 1.Which type of call control uses a call agent to route the call? 2.What is a DSP? 3.Name 3 types of analog interfaces used at gateways. 4.What are the 3 components of basic call control? 5.What phase of call control involves determining if bandwidth is available to place the call?

© 2006 Cisco Systems, Inc. All rights reserved. Summary  The benefits of a VoIP network include more efficient use of network bandwidth and equipment, lower cost and consolidated expenses.  Legacy analog and VoIP applications and devices can coexist.  The 3 stages of a VoIP call include call setup, call maintenance, and call teardown.  VoIP can be deployed in a centralized or distributed environment.