User manual

MX-ONE SYSTEM DESCRIPTION
52 21/1551-ASP 113 01 Uen N2 2014-01-28
• To enable the emergency call service, procedures described in
relevant operational directions must be followed carefully. It may
not be possible to provide fully transparent services depending on
the terminal types to dial the emergency number and the route
access code defined to locate the right emergency center. For more
details, refer to Operational Directions for Emergency Calls, SOS
Calls.
Considering the issues listed above, a remote MX-ONE unit (i.e. media
gateway with own local Telephony Server) rather than remote gateway
is recommended. In particular, the local survivability for non-disrupted
service may be a factor that motivates a distributed MX-ONE system or
an SBG, instead of remote gateway for branch node services.
5.1.2 Multi-Server Features
An MX-ONE Telephony System composed by several servers (previ-
ously called multi-LIM system) is in all respects a single PBX system. IP
extensions can register with any server of the multi-server system. With
the new HLR redundancy feature, an IP extension does not need to be
able to contact its home-server for registration although certain limita-
tions still applies. At installation, each server is assigned a server
number. Server 1 always runs Manager Telephony System (see 5.2.1
MX-ONE Manager Telephony System).
In a multi-server system one arbitrary server is assigned as master and
is constantly monitoring the other telephony servers by a mechanism
similar to that used in a Token Ring network. If one server fails or is
unavailable, the system will notice this and continues to work correctly.
If the master server fails, another server will take over this role. In a
multi-server system, the IP infrastructure (LAN) is used for inter-server
communication, both call control signaling and media. All signaling is
sent between the Telephony Servers over the LAN using a proprietary
protocol over Stream Control Transmission Protocol (SCTP). The media
streams are sent over the LAN using the Real-time Transmission
Protocol (RTP) protocol.
A group switch can also be used to send the media streams, but only
between single media gateway servers. If both parties in the call are IP
phones or IP clients, the media streams are sent directly over the LAN
between the parties. Note that both end-points must use the same
protocol. If one or both parties in the call are Time Division Multiplexing
(TDM) based or an analog phone, an IP gateway is used to bring the
party to the LAN. The media gateway has a built-in IP gateway
connecting the Primary Rate Interface (PRI) trunk lines to the LAN. The
Media Gateway Classic uses IP Line Unit (IPLU) boards as IP gateways
to the LAN. An MX-ONE that is upgraded or migrated to can use an
installed group switch, called GS. GS is placed in the same type of
cabinet as media gateways. The group switch only handles media and