Specifications

ENT_MLE_015989 - Ed 02_2014-10-13
Chapter 13: Topology – Network Services
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Alcatel-Lucent Enterprise Communication Solutions
April 2014 Offer
Call admission control on H.323 VoIP networks using internal mechanisms
CAC (call admission control) is used to prevent a new call from being routed over the IP network if
there is not enough available bandwidth. The call is rejected or is rerouted through the PSTN with
complete feature transparency.
Due to the characteristics of IP, it is not possible to dynamically adapt to the available bandwidth on
the network. However, the Alcatel-Lucent OmniPCX Enterprise Communication Server performs CAC
statically in two ways in an ABC network:
– Globally limiting the number of H.323/ABC calls on a node (e.g., if fixing a maximum of
ten incoming/outgoing calls, the eleventh call will be rejected)
– This solution is well adapted to IP networks with a star topology (a single WAN link per
node)
– Limiting calls per direction when the site has several WAN links to other sites. For
example, ten calls in direction one, five calls in direction two, etc.
This solution is well adapted to IP networks with a meshed topology.
Call admission control for SIP
CAC is used to manage the traffic for SIP phones in the same way as IP Touch phones or IP Media
Gateways as the SIP endpoints are registered in the Alcatel-Lucent OmniPCX Enterprise
Communication Server SIP Proxy.
A SIP phone making or receiving an intra-domain call will use the intra domain codec for the domain,
typically G711.
If the maximum number of domain calls is reached, the SIP phone will be forced to use the pre-
defined extra domain codec.
The CAC-SIP configuration (y/n) limits the number of SIP calls by domain to maintain voice quality.
Note: Video is not possible if CAC-SIP is enabled.