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What is the difference between T1 & E1 Lines?

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Question added by Amir Mohamed , IT Team Leader , The Xnet Systems
Date Posted: 2013/09/20
Mostafa Abdo
by Mostafa Abdo , Senior Infrastructure and Security Architect , Devoteam

T1 is a digital carrier signal that transmits the DS –1 signal. It has a data rate of about1.544 megabits / second. It contains twenty four digital channels and hence requires a device that has digital connection. This digital connection is called as the CSU / DSU – Customer Switching Unit or Digital Switching Unit. The scalability of the T1 is up to200 and above users. It also provides some services similar to the internet provider. Most of the computer uses a T1 connection. This technology makes your modem to have higher speeds and it is an affordable technology. 

E1 is similar to the T1. T1 is the North American term whereas the E1 is the European term for the transmission (digital). The data rate of E1 is about2 mega bits per second. It has32 channels at the speed of64 Kbps. It is important to know that2 channels among the32 are already reserved. One channel is used for signaling while the other channel is used for controlling. The difference between T1 and E1 lies in the number of channels here. The speed remains the same. There may be inter – connection between the E1 and T1 lines. This is interconnected because it is used for international purpose. 

هاشم المشارقة
by هاشم المشارقة , Key Account Manager , Advanced United Systems Ltd. ( A member of Taj Holding Group)

very good question

The main differences between T1 and E1 are the operating frequency or Data Rate, the number of time slots, the pulse shape, the characteristic line impedance of the line, and the signaling method

The T1 system operates at 1.544MHz with a total of 24 time slots. The T1 pulse shape contains overshoot and undershoot and is driven on a line impedance of 100Ω. Finally, digital messages to signal on/off-hook or other conditions are sent using robbed-bit signaling.

The E1 system operates at 2.048MHz with a total of 32 time slots. The E1 pulse shape is a perfectly rectangular pulse shape and is driven on a line impedance of 120Ω or75Ω. Finally, digital messages to signal on-/off-hook or other conditions are sent using channel-associated signaling.

samir abdulrahim
by samir abdulrahim , Senior Telecom & IT Consultant , STC

What are T1 and E1?

T1 is a digital carrier signal that transmits the DS –1 signal. It has a data rate of about1.544 megabits / second. It contains twenty four digital channels and hence requires a device that has digital connection. This digital connection is called as the CSU / DSU – Customer Switching Unit or Digital Switching Unit. The scalability of the T1 is up to200 and above users. It also provides some services similar to the internet provider. Most of the computer uses a T1 connection. This technology makes your modem to have higher speeds and it is an affordable technology.  

E1 is similar to the T1. T1 is the North American term whereas the E1 is the European term for the transmission (digital). The data rate of E1 is about2 mega bits per second. It has32 channels at the speed of64 Kbps. It is important to know that2 channels among the32 are already reserved. One channel is used for signaling while the other channel is used for controlling. The difference between T1 and E1 lies in the number of channels here. The speed remains the same. There may be inter – connection between the E1 and T1 lines. This is interconnected because it is used for international purpose.  

Differences in the physical delivery:

Here are we are going to discuss the differences in the physical delivery.

Data Rate: The main difference is the data rate. T1 has a data rate of1.544 mbps and E1 has a data rate of2.048 mbps.

Copper Delivery: In the T1 signal there is a copper delivery among4 wires. It is grouped into two pairs. One pair is the RX (1+2) and another is TX (4+5). The RX is the data that is from the network and the TX is to the network. In the E1, there are two types of physical delivery; balanced physical delivery and unbalance physical delivery. The unbalance physical delivery has4 copper wires. It is similar to that of T1. Whereas in the balance physical delivery there is a coax connector which has one cable for RX and one cable for TX.

Services: T1 has a specific type of service. It has repeaters for every six thousand feet, a pulse or waveform shape and a jitter. The E1 has32 timeslots. This can be said as DS. Each DS is about8 bits wide.  

Differences in the Framing Format:

Let us discuss the differences in the framing format.

Framing: In T1, there are two types of framing formats. One is D4 (twelve bits group) – used in aligning the equipment which is used for framing and another is ESF (twenty four bits group) – used in aligning the frames as well as in the maintenance of the channel which is facilitated by the data link. In E1, there are two framing formats. One is a called the double frame – it uses the DS0 and another is the multiframe which is the independent form.

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