22 Description
If the main office Signaling Server fails and an Alternate Signaling Server
is available, the SRGIP Phones reset and reregister with the SRG. The
SRG will then query the NCS for the Alternate Signaling Server IP address.
The SRG will redirect the IP Phone to the Alternate Signaling Server and
continue to receive call processing services from the main office Call Server.
If no Alternate Signaling Server is available, the SRG IP Phones reset and
register with the SRG in Local Mode.
When an IP Phone at the SRG first boots up, the IP Phone attempts
to communicate with the SRG. After communication with the SRG is
established, the SRG redirects the IP Phone to the main office. When
the SRG IP Phone attempts to register with the main office, the SRG first
queries the Primary NCS for the main office Virtual Trunk node IP address
to redirect the IP Phone. If the Primary NCS is down or unreachable, the
SRG queries the Alternate NRS (H.323 Gatekeeper/SIP Redirect Server),
if one is specified. If it receives a positive response, the SRG IP Phone is
redirected to the specified main office. Otherwise, if neither a Primar y or
an Alternate NRS (H.323 Gatekeeper/SIP Redirect Server) is available,
the SRG IP Phone remains in Local Mode, and receives call processing
services from the SRG until communication can be reestablished.
SRG IP Phones in Normal Mode remain registered with the main office
if the Primary NCS fails and no Alternate NCS is available. They can
call any main office telephone or IP Phones in Normal Mode in other
branch offices. However, they cannot call any SRG analog (500/2500-type)
telephones or any external numbers through the SRG trunks because an
H.323 Gatekeeper/SIP proxy server,which could route call proper ly in case
of an NRS failure, is not available.
Recovery to Normal Mode
After communication is reestablished with the main office call server, all IP
Phones at the branch office that are in Local Mode automatically redirect
and reregister to the main office and return to Normal Mode operation.
IP Phones that were busy at the time communication was reestablished
complete the call in Local Mode, and then reregister with the main office
after the call is complete.
Local Mode operation
When an SRG IP Phone is in Local Mode, the user has full access to
the services configured at the SRG (analog devices or analog or digital
trunks) and to other IP Phones registered to the SRG. In Local Mode,
the IP Phones can make local calls to other IP Phones and other analog
(500/2500-type) telephones at the branch office. They can also be used to
make outgoing PSTN calls and receive incoming calls as usual. SRG IP
Phones can access the main office IP Phones or other branches by routing
through the local PSTN.
Nortel Communication Server 1000
Main Office Configuration Guide forSRG 50
NN43001-307 02.02 Standard
Release 5.0 3 December 2007
Copyright© 2005-2007, Nor tel Networks
.