User's Manual

Survivable extensions
Survivable extensions support SIP phones only. For a list of supported telephones, see
Supported telephones on page 21. Voicemail for survivable extensions is provided by Modular
Messaging. When Modular Messaging is used as the central voicemail system, at each branch
you have the option to still use the local Embedded Voicemail for auto attendant operation and
for announcements to waiting calls. For more information about voicemail, see Voicemail
operation on page 163.
SIP extensions can be registered to the Communication Manager Feature Server at the central
headquarters site but be physically located at the B5800 Branch Gateway site. This mode of
operation is called survivable extension mode.
The survivable extensions can be configured to use the local B5800 Branch Gateway site to
make and receive calls when connection to the Avaya Aura
®
network is not available. When
this happens the B5800 Branch Gateway is acting as a survivable gateway for the extensions.
This can be in addition to trying to register with an alternate Avaya Aura
®
Session Manager.
Limitations
• WARNING — Survivable phones (also referred to as centralized phones) are not
provisioned from the B5800 Branch Gateway system. Centralized phones should be
configured to obtain their setting and firmware files from a source other than the B5800
Branch Gateway system, unless you use the procedure described in
96x1 phones SIP
firmware download in B5800 Branch Gateway centralized branch deployments on
page 84.
• Manual Configuration — For survivability operation, survivable extensions must be
added to the branch configuration manually. Auto creation of the required extension and
user configuration entries should not be used.
• Telephony Feature Restrictions — When registered with the B5800 Branch Gateway
system in survivability mode, the range of telephony features available to the centralized
phone will be limited compared to the features provided to the phone normally by the
Communication Manager Feature Server or Evolution Server.
Survivable extensions
Implementing the Avaya B5800 Branch Gateway November 2011 181