Smart Buildings Systems for Architects, Owners and Builders

During those years, the market was dominated by a few large companies
with systems open enough to connect to the outside world but that had pro-
prietary operating systems and core hardware. When deployed for larger
installations, those systems are referred to as private branch exchanges (PBXs)
and are essentially privately owned hardware that could connect and exchange
calls with the outside world (Fig. 10.1).

Voice over IP

The market for telephone systems significantly changed in the late 1990s with
the introduction of voice over IP (VoIP) technology. VoIP essentially utilizes a
data network based on the IP to transmit voice. It encodes analog voice into
digital data packets at one end and decodes the digital data packets into ana-
log voice at the other end. As the marketplace changed hybrid systems based
on both TDM and VoIP technology became available. The hybrid systems
are transitional systems allowing users to gradually evolve to VoIP technology.
VoIP has many advantages over the older TDM technology. A main selling
point of VoIP is that, as voice essentially becomes an application on a data
network organizations need only deploy a single network rather than separate
networks for data and voice. This results in savings, primarily related to the
consolidation of resources for management, administration, and maintenance
of two networks.
VoIP offers more functions and features through the true integration of
voice and data networks. Conventional TDM telephone systems had attempted

User

Telephones

Fax

Machine

PBX

Public

Switched

Telephone

Network

Figure 10.1 TDM PBX telephone system.

114 Smart Building Systems for Architects, Owners, and Builders