Lync Voice Mail Survivability (SA) with Exchange Unified Messaging
The SBA is aware of the centrally configured Exchange Unified Messaging
component. Additional it is important to understand the process of Voice Mail
Survivability. While the VoicemailReroutingConfiguration in Lync provides the
SBA with an alternative path, rerouted via PSTN to the central Exchange UM
site.
The SBA is continuously check the SIP availability of the Exchange UM
component, using the SIP OPTION based health checking. (Indeed, both SBA and
non SBA Lync registrars act in the same way for all components, e.g. Exchange UM
and other Gateway-SBC). Once the SIP OPTION command is sent, the sender expects
an SIP 200 OK answer. Lync tries this health check several time even after it
do NOT receive a 200 OK. As result of not receiving, the registrar will mark
this target as DOWN and stop sending calls.
Note:You can drill down this process, if you us OCSLogger and Snooper catching the OPTION and 200 OK communication directly on the SBA.
Note:You can drill down this process, if you us OCSLogger and Snooper catching the OPTION and 200 OK communication directly on the SBA.
Back to the Exchange UM, if Exchange is not responding, the SBA marks the
UM SIP path as down and activated the configured PSTN reroute.
Note:
Note:
If a user SBA homed user is remotely connected to central site (his backup
registrar), incoming PSTN call to this user will also be rerouted to Exchange
UM VoiceMail.
A PSTN cannot be rerouted this this (backup) registered user!
Voice Mail Deposit
If a WAN outage occurs, the SBA has detected that UM connectivity is down,
all unanswered or ignored call for effected user homed on this SBA will be routed
over the PSTN to the assigned UM Auto Attendant (AA).
There is one change in user experience: Once the UM pickup this call, the
AA will ask the calling party (either via speech or extension number) and then
a voice mail can be recorded. This behavior is different to the native user mailbox
response.
Voice Mail Retrieval
During a WAN outage, there are other service truly effected too, e.g. Exchange
Server connection. But Exchange Subscriber Access is still available via PSTN
calls. Therefor an effected user is NOT able to use his Lync Client for Voice
Mail Preview, instead, the normal “Call Voice Mail” will place a PSTN call to
the Exchange Server Subscriber Access Number (SA).
As long the user is assigned in AD and Lync with an E.164 phone number,
Exchange is able to do a Reverse Number Lookup and can identify the users work
number. Exchange then answer directly instead of asking for the user’s mailbox
PIN.
Configuration
Voicemail rerouting configuration must be established for all Branch Site equipped
with a SBA
New-CsVoicemailReroutingConfiguration -Identity Site:Ingolstadt
For each Voicemail Rerouting, the Exchange Auto Attendant (AA) and the
Subscriber Access Number (SA) has to be published.
Set-CsVoicemailReroutingConfiguration -Identity Site:Ingolstadt -SubscriberAccessNumber “+49899090123″ -AutoAttendantNumber “+49899090456″ -Enabled $true
Thanks to Justin Morris for his detailed explanation
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