Cisco Systems OL-14619-01 manual Packetization Sccp Integrations Only

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Chapter 6 Integrating Cisco Unity with the Phone System

Integrating with Cisco Unified Communications Manager Express (by Using SCCP or SIP)

Packetization (SCCP Integrations Only)

The Real-Time Transport Protocol (RTP) is used to send and receive audio packets over the IP network. Each discrete packet has a fixed-size header, but the packets themselves can vary in size, depending on the size of the audio stream to be transported (which varies by codec) and the packetization setting. This variable size function helps utilize network bandwidth more efficiently. Reducing the number of packets that are created per call sends fewer total bytes over the network.

Packetization is set in the Cisco Unified CM Service Parameters, in the Preferred G711 Millisecond PacketSize and Preferred G729 Millisecond PacketSize parameters. Cisco Unity supports any packet size up to 30ms for G.711 audio, and any packet size up to 60 ms for G.729a audio. The default setting is 20ms for both; there may be latency issues with lower settings.

DSCP is a priority setting on each packet. DSCP helps intermediary routers manage network congestion and lets them know which packets to prioritize ahead of others. Following Cisco AVVID standards, the Cisco Unity-CM TSP marks the SCCP packets (call control) with a default DSCP value of 26 (the TOS octet is 0x68), and the RTP packets (audio traffic) with a default DSCP value of 46 (the TOS octet is 0xB8). Thus, the RTP audio packets can be assigned priority over other packets by using the router settings. Note that even though Cisco Unified CM allows you set different DSCP values, when integrated with Cisco Unity, the DSCP values set by the Cisco Unity-CM TSP always take precedence.

With each new audio stream (once per call), Cisco Unified CM tells Cisco Unity which packet size to use, and the Cisco Unity-CM TSP sets the DSCP priority for the stream. The entire stream (call) stays at the specified packet size and priority. For example, an audio stream could be broken up into packets of 30ms each. A 30ms G.729a audio stream would be 30 bytes plus the header per packet, and a 30ms G.711 stream would be 240 bytes plus the header per packet. For information on setting Cisco Unified CM Service Parameters, see the Cisco Unified CM documentation at http://www.cisco.com/en/US/products/sw/voicesw/ps556/tsd_products_support_series_home.html.

Integrating with Cisco Unified Communications Manager Express (by Using SCCP or SIP)

Cisco Unity supports Cisco Unified Communications Manager (CM) Express (formerly known as Cisco Unified CallManager Express) integrations through both SCCP and SIP interfaces. Figure 6-8shows the connections.

Figure 6-8

PSTN

Cisco Unity SCCP and SIP Connections to Cisco Unified Communications Manager Express Over a LAN

Cisco

Unity server

Cisco Unified

Communications

Manager Express

LAN

191850

 

See Table 6-5for information on the differences in these integration methods.

 

 

Design Guide for Cisco Unity Release 5.x

 

 

 

 

 

 

OL-14619-01

 

 

6-17

 

 

 

 

 

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Contents Americas Headquarters Design Guide for Cisco UnityDesign Guide for Cisco Unity Release N T E N T S Workstations Authentication Centralized Voice Messaging Configuration Viii Document Conventions AudienceSupport Policy for Optional Third-Party Software Cisco Product Security Overview Xii Design Guide Overview Product Area Design or Feature DocumentationDesign Guide for Cisco Unity Bridge at Page Design Guide Overview Design Guide for Cisco Unity Release How Cisco Unity Works Cisco Unity ConceptsVoice Messaging Unified MessagingHardware Components of a Cisco Unity System Cisco Unity Supported Platforms List at One or More Cisco Unity ServersNetwork Connection Optional for Some Configurations Software Components of a Cisco Unity System Where Cisco Unity Stores DataVoice Messages Are Stored in Domino or Exchange DominoExchange Enabling Cisco Unity Servers to Communicate with One Another Networking Guide for Cisco Unity at Some Configuration Settings Are Stored in the Registry Availability of Network Resources Name ResolutionAvailability of Message Store Servers Domain Controller Access and AvailabilitySizing and Scaling Cisco Unity Servers Using Firewalls with Cisco UnityNumber of Voice Ports Storage Capacity for Voice MessagesHow Codecs Affect the File Size of Voice Messages Audio CodecsInteroperability Among Multiple Voice-Messaging Systems TTS, TTY, Pocket PCs, and Hand-Held ComputersAudio Codec Quality RatingDeployment Models Unified Messaging with Customer-Provided Infrastructure Multi-Site WAN with Distributed Messaging Voice Messaging with Customer-Provided InfrastructurePhysical Placement and Network Infrastructure Active Directory Considerations Considerations for Customer-Provided InfrastructureDesign Guide for Cisco Unity Release Exchange Considerations All Versions Exchange Considerations That Apply Only Exchange Considerations for Cisco-Provided, Dedicated Infrastructure OL-14619-01 Overview of Cisco Unity with Domino and Notes Domino Address Book Terminology Maximum Number of Cisco Unity SubscribersElement Name Changes That csAdmin Makes to the Domino Address BookChanges That csClient Makes to the Mail File Windows Domains and Domino Domains Server PlacementActive Directory Accounts and Permissions AuthenticationCisco Unity Subscribers and Domino Users Domino PermissionsDomino Clusters Cisco Unity and the Domino Address Book Client Access LicensesMessage Routing Backing Up and Restoring DataUnified Messaging, No Domino Cluster Unified Messaging ConfigurationsServers Requirements and Recommendations Criteria for a Supported Configuration Voice Messaging ConfigurationUnified Messaging, Domino Cluster Deploying Cisco Unity for Lotus Domino Network Services Administrative Access and ControlDeployment Tasks for Unified Messaging Configurations Establishing Support PoliciesOperational Tasks Design Guide for Cisco Unity Release Overview Integrating Cisco Unity with the Phone SystemHow an Integration Works Integration with Cisco Unified Communications Manager Lines and Cables to Make Physical ConnectionsDigital Integration with Digital Pimg Units Dtmf Integration with Analog Pimg Units LAN/WAN Timg IntegrationSerial Integration with Voice Cards Dtmf Integration with Voice CardsConnections for a Serial Integration by Using Voice Cards Settings in the Phone System and in Cisco UnityCall Control General Integration Issues Sccp SIP FeatureIntegrating Cisco Unity with the Phone System Option Considerations Description Cisco Unified Communications Manager Security FeaturesDescription Setting Effect When Data Is EncryptedDisabling and Re-Enabling Security Settings for Individual Voice Messaging PortsPacketization Sccp Integrations Only Sccp SIP Cisco 11 Cisco Unified Communications Manager Fallback with Pstn Cisco Unity to a branch office will fail Integrating by Using SIP Cisco Unity Failover with SIP Trunks Supported SIP IntegrationsSIP Compliance Description of Pimg Integrations Dtmf Integration with Analog Pimg Units Description of Timg Integrations Firmware Updates Serial Integrations Setup and ConfigurationCisco Unity Failover Increasing Port CapacityMultiple Integration Support/Branch Office Consolidation Cisco Unity FailbackIntegrating with Multiple Phone Systems Requirements for Integrations with Multiple Phone Systems Using Sccp Phone Systems with Other IntegrationsAlternate Extensions Optional Integration FeaturesReasons to Use Alternate Extensions How Alternate Extensions WorkMWIs for Extensions on a Non-Integrated Phone System Alternate MWIsCentralized Voice Messaging OL-14619-01 OL-14619-01 Failover Cisco Unity Failover and Standby RedundancyStandby Redundancy Cisco Unity Failover and Standby Redundancy Cisco Unity Failover and Standby Redundancy Pstn WAN Diagram of a Standby Redundancy ConfigurationOL-14619-01 Voice-Recognition Access to Cisco Unity OL-14619-01 Migrating to Cisco Unity from Another Voice-Messaging System Migrating to Cisco Unity from Another Voice-Messaging System D E IN-2 IN-3 IN-4
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