> private circuits

A private telecommunications circuit is used to connect two or more premises either to save costs or give a required quality of service. It can be used for voice and/or data communications.

The alternative to using a private circuit is to use generally available public telecommunication services that would typically have usage based charging. In contrast, private circuits would typically have fixed monthly charges and higher one-off set-up fees.

For example, if an organisation is spending  (say) £1,500 per month for telephone calls between two sites and it costs (say) £1,000 per month to rent a private circuit between the sites that could carry those calls then they would consider installing a private circuit between the telephone systems at each site.

As part of their cost calculation they would also need to consider the installation cost of the private circuit and the cost of equipment required to terminate the private circuit on the telephone systems at each site.

The provision of private circuits for telephone communication is usually a simple cost calculation since the service that is available from the public telephone networks is not significantly different from that which would be provided over a private telephone circuit.

However, for data communications there are typically service issues to consider together with costs.

In fact it is only recently with the growth of the internet that public data communications services have become available that have provided a viable alternative to private data communication circuits. Before the advent of the internet if an organisation wanted to connect remote sites to their data centre the only way of doing this was to have individual private circuits connecting the data centre to each site.

In other words a service was required and the only way of providing that service was to install private data communication circuits. Before the internet there was no direct cost comparison that could be made between private circuits and an equivalent public service.

It is now possible to use public internet services to deliver data communications between remote sites and a data centre, but these publicly available services are usually configured to mimic a private circuit in the form of a virtual private network.

Nevertheless, there are occasions when a real private circuit can either be justified on cost grounds or is needed for service reasons such as speed, availability and security.

In the pages that can be accessed from the links below we consider service and cost characteristics of the different types of private circuit that can be installed between two sites:

• virtual;
• local (ie within a single exchange area);
• long distance (ie between exchange areas); and
• wireless.

Despite the example at the top of the page, it is now rare that voice telephone private circuits can be justified on cost grounds since the cost of calls over the public network is now very low. Voice telephony is now just one of the applications that run on data private circuits, either real or virtual.

Please get in touch if you want advice on the best way of connecting two sites.