Chapter 2: System Overview System Reliability
ShoreTel 8 Planning and Installation Guide 15
The following features that require writing to the database will continue to be supported by
the server and not the switch:
Speed dial (due to its reliance on the database)
Ability to change call handling modes
Workgroup Agent Wrap up
Monitoring extensions on other switches
Presence information for user serviced by other switches
2.6.3 IP Phone Keep Alive
ShoreGear 1U Half-Width and 1U Full Width voice switches send a heartbeat to their
associated IP phones once a minute. If the heartbeat is not acknowledged within
approximately four seconds, the switch considers the IP phone to be offline or unavailable.
The switch continues to broadcast the heartbeat every minute. Any currently offline IP
phone that returns an acknowledgement is considered online and available.
2.6.4 IP Phone Failover
IP phones can be optionally configured to send a heartbeat to their ShoreGear switch every
four minutes. If an IP phone cannot communicate with its switch, the phone automatically
connects to another switch located at the same site. For IP phone failover to be effective,
the system must be planned with sufficient excess capacity to handle phones from at least
one switch during a failover event. For example, if a switch with 20 IP phone ports fails, 20
IP phone ports need to be available elsewhere at the same site.
The feature allows an administrator to configure the system so there can be failover of
phones from one switch to another in the case of a switch failure. The feature is not
intended to provide failover for network outages (i.e. or lost connectivity between the
headquarters server and a remote site). Some network outage scenarios may be handled by
the ShoreTel failover solution.
Failover will occur on a phone by phone basis and will be driven by receiving RSIP from
the phone. IPCS will not move phones other than the one sending RSIP. Each phone must
initiate its own failover.
For configuration details, see the ShoreTel 8 Administration Guide.
2.6.5 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
The PSTN failover option must be explicitly enabled for each user and bypasses the caller’s
call permissions. For configuration details, see the ShoreTel 8 Administration Guide.
For systems using the Distributed Routing Service (DRS), PSTN failover for outbound calls
will not function when the local switches lose connectivity to a DRS server. When a site
does not have connectivity to DRS, users at other sites with DRS connectivity will be able to