Examining Multisite Connection Options ccsp bootcamp training center in delhi gurgaon india

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Multisite environments have several connection options; Figure 3-1 shows a CUCM cluster
at the main site, with three connections to other sites.
Figure 3-1 Connection Options for Multisite Deployments
Main Site Remote Cluster
The connections are as follows:
• Intercluster trunk (H.323) to another CUCM cluster located at a different site
• An H.323 gateway located at a remote site
• A session initiation protocol (SIP) trunk connected to an Internet telephony service
provider (ITSP) via a Cisco Unified Border Element (CUBE), which also has a SEP
trunk to CUCM
• At the remote location an MGCP Gateway is configured to be controlled by the remote
cluster CUCM.
Examining Multisite Connection Options 55
MGCP Gateway Characteristics
A Media Gateway Control Protocol (MGCP) gateway uses the centralized call-processing
model, so the gateway does not have a local dial plan and does not perform call processing on
its own. Although an MGCP gateway does have dial peers, there are no phone numbers of
the dial plan in the gateway. Instead, the gateway relies on a call agent such as CUCM that
controls the gateway and its interfaces. Unique features on Cisco IOS MGCP gateways that
are not supported by H.323 or SIP gateways include the following:
• Centralized provisioning
• Q Signaling (QSIG) supplementary services (QSIG is supported in an H.323 trunk)
• Centralized Call Detail Record (CDR) digital service level 0 granularity in CUCM CDR
• Multilevel Precedence and Preemption (MLPP)
• Hookflash transfer with CUCM
If any of these features are required, MGCP signaling must be used with the gateway.
NOTE Hookflash transfer with H.323 gateways is possible via a Tool Command
Language (TCL) script, which you can download from Cisco.com.
H.323 Gateway Characteristics
H.323 gateway uses the distributed call-processing model, so the gateway has its own local
dial plan with dial peers and performs call processing on its own. It does not rely on any
other device but can be configured to work with CUCM or other H.323 devices. Unique
features on Cisco IOS H.323 gateways not supported by MGCP or SIP gateways include
the following:
• Non-Facility Associated Signaling (NFAS), which allows more than one ISDN PRI
to be controlled by a single ISDN D channel
• TCL/Voice Extensible Markup Language (VoiceXML)
• Integrated voice and data access
• Fractional ISDN PRI
• Time-division multiplexing (TDM): analog direct inward dialing (A-DID), ear and
mouth (E&M), PRI NFAS, Centralized Automated Message Accounting (CAMA),
Tl Feature Group D (FGD)
Chapter 3: Implementing Multisite Connections
• TDM T3 trunks
• Set the numbering plan type of outgoing calls
• The ability to reject an incoming call from the PSTN based on ANI
• If any of these features are required, H.323 signaling must be used with the gateway.
NOTE Fractional PRI support with MGCP is possible when you limit the timeslots
manually at the MGCP gateway and busy out B channels in CUCM (using an advanced
service parameter). However, this configuration is not officially supported.
SIP Trunk Characteristics
Session Initiation Protocol (SIP) uses the distributed call-processing model, so a SIP gateway
or SIP proxy device has its own local dial plan and performs call processing on its own. A
CUCM SIP trunk can connect to Cisco IOS gateways, a Cisco Unified Border Element, other
CUCM clusters, or a SIP implementation with network servers (such as a SIP proxy).
SIP is a simple, customizable protocol with a rapidly evolving feature set. SIP is an Internet
standard, and its support is rapidly growing in the VoIP marketplace.
NOTE When you use SIP trunks, Media Termination Points (MTP) might be required
if the endpoints cannot agree on a common method of dual-tone multifrequency (DTMF)
exchange.