T1 Line - A Complete and Comprehensive Guide

What is T1 Line?

Have you heard of the latest internet technology that was developed by the AT&T Bell Labs that is being utilized in North America and Japan? It is described and referred to as a particular type of copper or fiber optic telephone line that has the ability of handling more data compared to that of telephone lines. Have I already stirred your curiosity? Lo and behold as we make way for this latest development, the T1 line. A T1 line has the capacity of transmitting 1.544 Mbps and it can also be used to send 24 digitized voice channels that can be used for phone service in commercial buildings and other establishments.

In the past, twisted copper telephone lines were the standard that lasted for decades. These copper lines were used for the transmission of voice and data through analog signals. As time progresses, the standard also was slowly upgrading into fiber optic lines out of bundled glass fibers, however, most T1 lines used today are still made of twisted copper. T1 lines created a 'pipe' which, as I have mentioned earlier, makes it capable f blowing through larger data streams.

The price, however of this amazing T1 line can be very expensive. But don't you guys fret since it has been a tradition in the world of technology that costs can increasingly drop when the demand grows. Internet service providers or commonly known as ISPs are very accommodating their clients when they wan to lease T1 lines to provide service to their wide network of clients. There are also other multiplexed fiber optic lines such as T2 and T3 lines and they has the capacity to transfer data to up to 44.736 Mbps. T3 lines are equivalent to having 28 T1 lines and is being utilized by larger establishments that has higher data and voice needs and demands. There are also more advance T-standards that are existing but they are not high in use.

Meanwhile, the European Union uses a different and incompatible type of carrier line which is called as the E1 and the E3. E2 lines are available as well but these types of lines are less common.

In general, T1 lines can not be cost-efficient for voice and data cabling individual or residential use and in this case, having a DSL or a cable service could be the better choice. Small businesses and government agencies, on the other hand - specifically those that are using PBXs can greatly benefit from a T1 line.

Types of T1 line

T1 circuits are oftentimes referred to as 'always on' connections. It does not resemble a voice circuit that can only yield expenses when a call is placed. With this reason, T1s are sometimes used as private lines or dedicated data lines because they are always utilized even though the data is being transmitted or not. Hence, it can never be used for handling traffic coming from multiple subscribers.

However, the most obvious downside of having a T1 line is its cost. T1 lines provide very fast and dependable connections, but you will pay for that guaranteed uptime. For a lot of businesses that depend heavily on employee and customer access to data and other applications, I assure you that T1s are really worth the investment.

Here are some types of T1 lines that they offer depending on what your company suites best. In its basic sense, T1 lines are used to carry either voice or data requirements.

1. Integrated T1's which offer voice and data that is carried on the same digital circuit. You have the freedom in deciding how much of the T1 connection's 24 channels can be used for voice calls and the remaining channel can be used for data.
2. Fractional T1's utilizes only a part of the total bandwidth for the percentage of a full T1 rate.
3. Burstable T1's are the ones that are "pay as you go" services. This type of T1 line offers a set amount of bandwidth at all times, however, it also has the capacity of tapping into a much greater bandwidth at times when there are high traffic spikes.
4. Bonded T1's are the kind that provides a full bandwidth coming from multiple T1s all at once making it suitable for a better speed and performance. The combination of single T1s into a single pipeline permits more bandwidth compare to two separate T1 lines.

Now bear in mind that when you have finally decided what type of T1 you are going to avail, then I am pretty sure that there will always be a contract signing. The contract that you will be signing for T1 line access must be comprehensive, without unwanted surprises or hidden fees - which mean putting all costs, length of service and the SLA in full detail.

The standard contract length for T1 line access is three years and may include all the set-up fees, installation costs as well as equipment rental. Now, if ever you break the contract early, then anticipate forking up several hundreds of dollars up to the balance that is left on the contract.

How does a T1 line Work?

In its general aspect, a T1 circuit is an "always on" type of connection and since T1 lines are dedicated circuits, they cost more compared to ISDN or Frame Relay circuits which thinks that the customer's connections are shared with other networks.

T1 circuits are the first ones which are in a multiplexed level of digital signaling multiplexing scheme. T1 lines use those Stratum 3 Clocks so that it can maintain what is referred to as the clocking on the line. The equipments that are used in supporting T1 lines estimate its synchronization with a T1 based on the data which is received over a link; hence T1 communications are fully synchronous all the time due to the frame slips. T1 lines should be called rather as pleisiosynchronous connections.

A T1 line's speed can reach up as high as 1.544 Mbps on the circuit. T1s are the most common high speed circuit that are being provided by the telecommunication carriers because T1s can be regenerated and extended to reach any place. T1 lines also handle 24 channels of digital information and must keep a certain level of 1s density so that there is an assurance that the clock is maintained at the circuit's both ends.

On its electrical aspect, T1 lines use the bipolar signaling method where the voltage states the range between +/- 12 volts. Binary zeroes are signaled with zero voltage. The binary ones are signaled with the use of either a positive or a negative voltage which is referred to as polarity. When the series of 1s are received on a T1 link, then the voltage changed from a positive to a negative voltage. From this alteration of voltage, the receiving equipment can detect and synchronize with the remote equipment's clocking. Zeroes are being indicated by the zero voltage on the line.

Finally, in the voice and data cabling aspect, twisted pairs are used within the communications network. One pair used for transmission, and the other is used for the receiving part, making four wires for each T1. This permits the T-carrier systems in sending and receiving concurrently in both directions at a full speed or full duplex. The T1 line trunk cables are made in bundles which come off as 25 pairs of 22 AWG copper wires which are especially designed for handling multiple T1s. The trunk cables can handle multiple bundles of the 25 pairs and the standard method that is being used for the carrying transmission is to differentiate transmit from receive onto each pair into separate bundles to decrease cross talks. Every now and then, a few extra pair is being added to these bundles for line management functions that include fault location or provisioning.