Many businesses that depend on data communications for revenue or have several thousand internet users are already considering upgrading the connection they have to the internet or telecommunication infrastructure. A growing number of these companies are opting for T3 service in one of the available configurations. A few techies from the early days of the internet may remember when T1 lines were the holy grail of connectivity. T1 lines are common place today. Growing demand for bandwidth is making the next level of connectivity an object of discussion in IT departments all over the country.
With bandwidth equivalent to 672 DS0 lines or 28 T1 lines, T3 lines are the next level. This is 44.7 Mbps. Unlike T1 service, T3 service cannot be carried over conventional twisted pair copper wires. The minimum requirement is two 75 ohm coaxial cables with BNC connectors from the local phone company site to the end user’s network interface unit. This connection is called the local loop. Increasingly, the local loop is being carried over fiber optic cable running SONET technology.
While they are often used interchangeably the terms DS3 and T3 are the same. When data communications discussion get technical it is important to understand the difference. The multiple DS0 lines or DS1 lines are multiplexed into a system that can be carried over a T3.
The transmission rate for T3 lines (44.7 Mbps) is not some arbitrary number. It is designed to make the multiplexing operation simple. Timing and framing of the combined signals combine naturally within the DS3 standard and are fully compatible with the T3 transmission rate. An unchannelized T3 line is configured as one 44.7Mbps data pipe to the internet.
The cost of installing and maintaining the local loop is the local phone company’s contribution to the total cost of a dedicated line. Major phone companies have individual methods of calculating rates for mileage charges between the phone company’s port and the end user’s network interface unit. This charge is not included in the T3 line provider’s lease rate. Installation charges are sometimes waived if a long term contract is signed.
The bandwidth of a dedicated line is the most obvious benefit. For most businesses the reliability of a leased line is just as important. Lease contracts include guaranteed service availability – often better than 99.7%. Other service factors are also specified. Maximum latency, maximum error rate and other service-related factors are included in service level agreements.
The service provider can be subject to reduced lease payments or charge-backs when service quality or availability does not meet agreed standards. This is significant incentive for the provider to restore interrupted service quickly.
Businesses can take advantage of the volatile pricing caused by the intense competition between carriers and lock in some very attractive lease rates. There are several websites offering price comparison services. Understanding an organization’s current and future data requirements is the first step. Then research into the local availability and lease rates for the required service level will pay off with a favorable lease agreement. Some T-carrier providers are offering fractional T3 and burstable T3 for businesses that do not need the full bandwidth all the time.