The KTS and PBX models

The other two system models are private telephone systems installed on the  company’s premises. Low-volume customers often  use a key telephone system, or KTS. High-volume, larger  companies often  use a private branch exchange, or PBX. These two are a departure from the POTS-line model, where a line is run to each phone on the  premises. As such, they  are also  a departure from the  Centrex model, which uses the same type  of access line as POTS.

One big benefit of private telephone systems is that they  reduce the number of required access lines.  For example, the  industry standard is one access line for every  six to eight  employees who have  a telephone. Any reduction in the  number of access lines  represents an enormous cost benefit for compa-
nies  when  compared to the  POTS or Centrex models. In addition, private tele- phone systems enable the  company to provide most traditional call features, such as voice  mail, call forwarding, call transfer, and conferencing, to any telephone in the  company — at no added cost.