How T1 and E1 Lines Compare

Two of the most popular digital line services for voice and data are T1 and E1. Depending on where you are located, you are probably familiar with one of these services but not the other. That’s because they are geographical standards. If your business crosses international borders, you’ll want to be familiar with both telecom standards.

T1 service is found in the United States, Canada, Japan and South Korea. E1 is used in Europe and most other areas of the world. I mention Europe, because that’s where the “E” in E1 comes from. The “T” in T1 means T-Carrier. It is a standard developed by Bell Labs right after WWII and used to provide trunking of multiple telephone calls between switching centers. Later, both T1 and E1 moved beyond their telephony heritage and became popular for digital data service to businesses and other organizations. Both are still highly popular today.

The reason to discuss T1 and E1 at the same time is that they are more alike than different. Both were based on digitizing telephone calls and transmitting them in channels of a time division multiplexed bitstream. Each channel is called a DS0 and is 64 Kbps in size. The physical interface is two pair of twisted pair copper telephone lines, the same type of lines that are used for home and business phone service. One pair is used for transmit and the other pair is for the receive channel. By keeping transmit and receive separate, you can talk and listen at the same time - a requirement for phone calls. This is often referred to as full duplex operation.

It’s no accident that T1 and E1 are so similar. The United States developed its standard first. Europe copied most aspects of T1, but added some improvements for their standard. The biggest difference is in the line speed or bandwidth. T1 lines run at 1.544 Mbps. Of that, 1.536 Mbps is used to transmit information called payload. The other 8 Kbps is for synchronization and maintenance functions. T1 lines have 24 time slots that carry 24 DS0 channels. Each channel can be one telephone call or all 24 time slots can be used to carry data at a bandwidth of 1.536 Mbps. This BW is often referred to as 1.5 Mbps.

E1 lines run at 2.048 Mbps. That bandwidth transports 32 time slots. Unlike T1 lines, E1 lines assign one time slot or channel specifically for synchronization and maintenance. Another time slot is generally reserved for signaling. Thus, an E1 line supports a user payload of 1.920 Mbps in 30 time slots or 1.984 Mbps in 31 time slots. This is often referred to as a bandwidth of 2 Mbps.

It should also be mentioned that while Japan uses the T1 line standard of 1.544 Mbps, there are differences in the use of the synchronization and maintenance bits. A T1 line in Japan is called a J1 line.

While there are numerous subtle differences between T1, E1 and J1, these are accommodated by the specific circuit design of the appropriate interface cards. At the switching centers, it is relatively simple to interface these lines due to their common heritage. You should have no problem connecting telephone calls or data transfers between any of your worldwide locations. It’s worth noting, however, that E1 lines accommodate more phone lines or data bandwidth per line than T1 lines.

Does your organization have a need for voice and data connectivity at any line speed required? It’s easy to have our expert Telarus consultants check bandwidth prices and availability for all of your locations worldwide and make recommendations to save you the most money on your telecom needs.

Business Booming For Telx Interconnection and Colocation

While many companies remain hunkered down and wringing their hands while they wait for the economy to improve, colo provider Telx is on a building boom at their premier data center in Chicago. What kind of sense does that make in recessionary America?

It makes lots of sense if you’re clued-in to what is transforming business and finance. It’s been a long time since accountants wore green eye shades and engineers worked slide rules. Most companies have adopted computer-based workstations connected to servers in the back room. This client-server architecture had a lot to do with increasing the speed of doing business and improving employee productivity in the last few decades. But now some of the savviest companies are adopting new methods and systems to give themselves an edge over their competitors.

Remember when the original justification for computerizing processes was elimination of paper? The “paperless office” became a joke as cheap laser printers and copiers spit out reams of paper faster than they could be hauled to the recycling bin. But when you consider how the speed and volume of transactions has increased, every desk should be piled to the ceiling and the aisles crammed full of paper documents. All the paper you don’t see is in the form of bits and bytes on hard drives spinning away inside your computer and in network storage within the data center. It’s turned out that less paper is the minor benefit of computerization. The big benefit is speed.

We simply do more faster. Companies don’t mail us product brochures anymore. We pull them up online. The time from identifying a need to researching solutions to placing an order has shrunk dramatically. It can all be done from the comfort of the desktop, sometimes in a matter of minutes. Need to coordinate team activities? Let them collaborate online so that those in Seattle can mark up documents for those in New York in real time.

Nowhere has the demand for speed become more dramatic than in the financial industry. You’ve heard of high frequency trading? These are complex algorithms running on high speed servers to electronically issue buy and sell orders to the markets. We’re at the point where milliseconds and even microseconds make a difference in trade profits. The Einsteinian limit of how fast light can move through glass and wire introduces a time delay between locations that simply can’t be reduced. So, how do you beat the competition? You get closer to the markets... physically closer. That’s what Telx provides. Its proximity to the exchanges and the buy-side and sell-side firms at Telx’s strategically collocated facilities. If the upper limit to your potential speed of transaction is a length of patch cord, you are in an advantageous position compared to the competitor hundreds or thousands of miles away.

Low latency colocation facilities near the action are essential for the most advanced players in high frequency finance. But there are other reasons for collocating with suppliers, customers and service providers. The cost of bandwidth is a good reason. With many competing carriers within arm’s reach, or at least down the hall, you’ve got access to the best rates per Mbps or Gbps and none of the expensive build-out costs of stringing wires or fiber cable for miles. If bandwidth is becoming one of your biggest expenses, moving to the colo facility can be a major cost saver. This can easily be the case if your product is video or high volume e-commerce or a popular application with millions of users.

Even smaller companies that aren’t located in a downtown sweet spot for low bandwidth prices may find that colocation gives them the advantage of keeping their physical location where it is but moving their bandwidth-hungry applications to where costs are lower. Cloud computing is another way to leverage the economy of scale in putting the software and servers where the bandwidth is cheapest and accessing the service from wherever you choose to be.

Does your company have demands for low latency or high bandwidth that would benefit from Telx or similar facilities? Are you just looking for ways to reduce your bandwidth costs? If so, you should take a look at the cost advantages of colocation and cloud computing services.