Converging Networks

Note the  absence of any POTS lines or pri- vate  telephone systems (KTS or PBX) under the  DS carrier service network cloud. All telephone calls are originating on the  company’s computer network using  VoIP. Only calls destined for the  PSTN are diverted off the  company’s network.

These types of calls,  referred to as off-net, are the  only calls that may be associated with a recurring service charge. For customers and com- panies running VoIP, off-net calls typically are only the  calls that go to the  public network (for example, to order a pizza  or to call 911). On-net calls require no additional lines  over  the  existing computer network setup and,  unlike  POTS-PSTN calling,  have  no additional recurring charges.

A smaller company with just  a single  location may use VoIP to connect their computer network to the  PSTN to support calls that must travel off their pri- vate  network. This solution requires installing a VoIP gateway that can con- vert the  company’s on-net traffic to circuit-switched telephone calls that have  an off-net destination. For example, a call from your  desktop phone to the  grade school that your  daughter attends is likely to be a local PSTN call.
Converting  VoIP telephony traffic to run on the  PSTN is certainly a big benefit of VoIP, but  many  more  exciting features and  benefits are explained in the  chapters that follow. For example, in Chapter 3, I describe how VoIP reduces or eliminates those nasty,  pay-by-the-minute service charges and other recur- ring charges such as regulatory fees and  taxes.