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PBX "Private Branch Exchange"—a term from the traditional
telephony world where customers received phone lines and needed a device on
their premises to connect those lines to handsets.
The
Session Initiation Protocol (SIP) takes that to the next level and
makes the PBX a software component in the computer network. The
PBX can also be hosted at Peopleline's network service centre so that
you do not need any PBX software or hardware at your location.
SIP is changing the telephony landscape like HTTP changed the publishing
world. By using SIP, you can combine services and devices from different vendors to build your
telephone system.
1. The PBX server or appliance is the core of the enterprise
communication system. The PBX server can either be installed on site at your location or hosted at our network centre.
2.
When installed at your location, it is connected to your local area
network (LAN). When installed at our lnetwork centre, you simply need to
install IP phones on your LAN.
3. Typically most of the SIP-phones are registered inside
the LAN to the PBX. They can make internal calls and check their mailboxes.
4. The PC in the network can access the PBX through the LAN.
This makes computer telephony-integration simple. The PBX can initiate phone
calls from an address book, run soft phones that are registered to the PBX
and/or use the web browser to log into the PBX and change settings, initiate
conference calls or check call lists.
5.
If the LAN contains WiFi access points, cordless devices can be
registered to the PBX just like other SIP devices. If the access point
includes routing functionality, the WiFi phones can hang off a
subnet. DECT-enabled devices are registered as regular SIP phones.
6. To make phone calls to the PSTN, typically a
PSTN gateway is being employed. This ensures there is excellent audio
quality and that phone calls are possible, even if the Internet connection is down.
7. Calls can be routed to PSTN destinations such as analog phones.
8. Calls to cell phones that are associated to extensions
are also run over the PSTN gateway. These calls can run in parallel to the
ringing of internal extensions and whoever picks up first will get the call.
9. Companies will use the public
Internet in their communications.
10. To reach the Internet, the PBX must go
through a firewall. This can be done by assigning a second IP
address to the PBX which can be routed from the public Internet.
11. Regular SIP phones can be registered through the public
Internet. The built-in mini-SBC of the PBX will take care about home DSL routers
and make sure that those phones can register to the PBX.
12. If public WiFi access points are available, the PBX can
even keep registrations of WiFi-enabled cell phones alive and integrate them as
regular extension into the corporate communication infrastructure.
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