> baseband connections


Baseband connections are a little known private circuit option for customers who need to connect premises that are within the same BT exchange area. In such cases it is possible to order from BT a relatively inexpensive private circuit known as a baseband private circuit (previously known as an EPS8 or EPS9 circuit).

A baseband private circuit is simply a continuous metallic path comprising one or more pairs of wires between two end points. In theory, it is possible to create a private baseband circuit between two buildings by running a pair of wires (by whatever means possible) between the two buildings. That is not usually practical, but BT can achieve the same effect by connecting, at the local exchange, the telephone cables that serve each building.

It is important to note that BT don’t guarantee the performance of a baseband private circuit in terms of data rates or quality of service. It is up to the customer to achieve the best possible performance using their chosen terminal equipment.

The terminal equipment used on baseband private circuits is known generically as baseband modems. These are similar to the broadband modems that are used for general purpose internet access.

There are different types of baseband modem that use different modulation techniques to achieve the highest performance. The most common types are VDSL2 and SHDSL.

In general VDSL2 performs better at distances of less than 500 metres with SHDSL able to operate effectively at distances of up to 2,000 metres and possibly more.

[NB When calculating the distance between two sites it is necessary to add their distance as the crow flies and then multiply the total by 1.5 to take account of the circuitous route that the BT cable may take to get to the exchange from each building.]

Some baseband modems can bond multiple baseband private circuits together to achieve higher speeds.

The reason that a baseband private circuit is significantly better than a virtual or standard private circuit is that it does not use the internet. There is therefore no congestion or contention for the available bandwith. Furthermore, the latency is significantly less with a baseband circuit since the telecommunications traffic is routed over the shortest possible distance rather than via an internet server in a distant location.

Consequently, a baseband private circuit with a speed of 20 Mbps will “feel” significantly faster than a virtual private circuit of the same quoted speed.

In addition to better performance, the key benefit of a baseband privates circuit is that they can provide equivalent speed at significantly lower prices than standard private circuits. In other words a 10Mbps baseband circuit between two buildings in the same exchange area would cost significantly less than a 10Mbps private circuit (between the same buildings) rented as a service from a public telecommunications provider.

The main drawback of baseband private circuits is that they are limited to connecting premises in the same exchange area and that the maximum speed (ie data rate) that can be achieved reduces as the distance between the premises increases.

When considering using baseband private circuits it is important to note that even if two premises are within the same exchange area it may not be possible to set up a usable connection simply because the baseband connection is over too great a distance.

This is similar to the situation with standard broadband services in that if the premises are more than 4.5 km from the local exchange then it is unlikely that it would be possible to provide a broadband internet service.

Get in touch with us if you have a specific requirement or if you wish to discuss how your business could make better and more cost-effective use of its existing telecommunications and internet infrastructure and services.