Specifications

ShoreTel Architecture Distributed Database
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Telephony operations involving locally controlled phones are available. Monitoring of phones
controlled by TMS instances not reachable because of WAN outage are not available.
TMS continues to operate, except that additions and deletions to the configuration database are not
been seen by local TMS and are not relayed to telephony clients. Telephony operations involving
locally controlled phones are available. If a WAN outage results in the loss of connectivity to one or
more switches, telephony operations with those switches is unavailable.
Distributed Database
ShoreTel supports a distributed ShoreTel database that allows some actions previously requiring
access to the HQ server. Prior to ShoreTel 11, users of ShoreTel Call Manager (now Communicator)
were able to change their call handling mode (CHM) only if the Headquarters server was available.
With ShoreTel 11 and later, changes to users’ CHM are handled by the local ShoreTel server (if
configured appropriately), even if the Headquarters server is not available.
Client Application Server (CAS)
Some features that require writing to the database depend on the server being both operational and
accessible. These features are handled by CAS on the server:
 Directory
 Options
 Speed dial (due to its reliance on the database)
 Ability to change call handling modes
 Presence information for user serviced by other switches
Public Switched Telephone Network (PSTN) Failover
User extensions can be optionally configured to route extension-to-extension calls to the public
switched telephone network (PSTN) in the event that an IP connection is unavailable. Extension-to-
extension calls are those a user makes to another site within a multi-site system, for example, a user in
New York calling a co-worker at the company’s San Francisco office.
The IP connection may be unavailable due to lack of bandwidth or connectivity. The PSTN failover
option must be explicitly enabled in the user’s Class of Service and bypasses the caller’s call
permissions. For systems using Distributed Routing Service (DRS), destinations allowing PSTN
failover return a contact list with a failover number.
Assuming that the users have the proper permissions, when a remote site without a distributed voice
server loses WAN connectivity, if DRS is disabled cross-site extension calls from the remote site would
still happen because of PSTN failover. If DRS is enabled, however, PSTN failover would not work
because DRS lookup is required to determine the PSTN failover destination. (If DRS is unreachable
because of a network issue, it is not possible to discover the PSTN failover destination.) This limitation
impacts remote sites that do not have a local DVS.