What is T1 and E1?
T1 is a digital carrier signal that transmits the DS – 1 signal. It has a data rate of about 1.544 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 to 200 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 about 2 mega bits per second. It has 32 channels at the speed of 64 Kbps. It is important to know that 2 channels among the 32 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 of 1.544 mbps and E1 has a data rate of 2.048 mbps. Copper Delivery: In the T1 signal there is a copper delivery among 4 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 has 4 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 has 32 timeslots. This can be said as DS. Each DS is about 8 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. | 
