What are SRST and MGCP fallbacks?

 SRST (Survivable Remote Site Telephony) and MGCP (Media Gateway
Control Protocol) fallback are two features in Cisco voice networks that
help ensure the availability and reliability of voice communications in the
event of a network outage or other disruption. These features are designed
to provide backup support for voice communications, helping to ensure that
users can continue to make and receive calls even if the primary network
connection is unavailable.


SRST is a feature that allows Cisco IP phones to automatically switch to a
backup mode of operation in the event of a network outage. With SRST
enabled, IP phones are configured to use a local call-processing engine,
such as a router or switch, to handle calls when the primary connection to
the main call-processing server is lost. This allows users to continue
making and receiving calls even when the primary network is
unavailable.


MGCP fallback is a similar feature that provides backup support for Cisco
voice networks using MGCP-based call control. With MGCP fallback enabled,
Cisco voice gateways are configured to automatically switch to a backup
call-control server in the event that the primary server is unavailable.
This allows users to continue making and receiving calls even when the
primary call-control server is down.


Both SRST and MGCP fallback are important features for ensuring the
availability and reliability of voice communications in Cisco voice
networks. By providing backup call-processing support, these features help
to ensure that users can continue to make and receive calls even in the
event of a network outage or other disruption.

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There are some potential drawbacks to using SRST and MGCP fallback,
however. One concern is that the backup call-processing engine may not have
all of the features and capabilities of the primary server, which could
limit the functionality and performance of the voice network during an
outage. Additionally, configuring and maintaining backup call-processing
engines can be complex and time-consuming, requiring careful planning and
coordination.


Despite these concerns, SRST and MGCP fallback remain important features in
Cisco voice networks. When used appropriately, these features can help
ensure the availability and reliability of voice communications, even in the
event of a network outage or other disruption. As voice networks continue to
evolve, it is likely that SRST and MGCP fallback will remain key tools for
maintaining the availability and reliability of voice communications in
Cisco networks.