Transmission System 3 (T3) is a high-speed transmission system designed to transmit information signals, and it transmits at 44.736 Mbps when channels are logically divided up into Time Division Multiplexing (TDM).

T3 is a fast information transmission line that is regularly utilized in territories requiring high bandwidth speed and continuous information transmission. These are territories that hold a huge store of information assets, like enormous connections, gigantic networks, or research centers. In huge networks, these lines give a dependable connection that can be utilized to assemble the foundation of a companys network system.

As T3 lines are symmetrical and duplexed, implying it offers equivalent download and upload speed, it likewise empowers concurrent information transmission without bringing about any traffic in the network. T3 is likewise alluded to as Digital Signal 3 (DS3).

What will we learn?

  • T3 Framing Structure
  • Classifications

1. M13 Asynchronous Framing

2. C-Bit Parity Framing

  • History

T3 Framing Structure

A T3 line conveys 672 channels that each run at 64 Kbps. To make a solitary transmission line from these channels, a T3 connection depends on a TDM which is fundamental since it has capacities as a multiplexer that intertwines the information channels. A multiplexer is like a digital switch that acknowledges the individual channels and has a solitary yield. These computerized signals are multiplexed throughout various time allotments, empowering a few channels to be carried on a similar information line. This is additionally why each channel is likewise called a timeslot.

A TDM takes input signals such as simple sign signals. They are first encoded and deciphered by the PCM, which converts 8000 inputs to a single 8-cycle esteem. This is conveyed at a rate of 64 Kbps. The 8-bit digital esteem and base speed, or DS0, is the unit that defines this information channel. These rates are increased in increments by multiplexing them into higher limits. This is the irony of the multiplexing cycle: it is octet-situated, based on a 8-digit esteem system.

At first, a T3 line begins as a group of four of T1 lines multiplexed to make a T2 line. Each T1 edge of information contains the 24 channels, each conveying 8 pieces of information, alongside an extra outlining bit that attempts to synchronize the information outlines. The 4 T1 lines make a T2. A M13 (Multiplex T1 to T3) does this and furthermore multiplexes a bunch of 7 T2 lines to shape the T3 transmission line. With each channel running at 64 Kbps, a speed of 42.924 Mbps is accomplished through these layers of multiplexing. Also, stuff bits capacity to help in flagging and control of information transmission. In general, a T3 line can give a connection accelerate to 44.736 Mbps.

A 4 wire bent pair circuit can fill in as the transmission mode of a T3 correspondence pathway, in any case, the sign wont run for more than 50ft. Utilization of current wiring innovations like coaxial links, and optical strands, or even microwaves are more reasonable to do this kind of information transmission.


There are various kinds of DS3 framing protocols. For the most part, 4 T1 lines structure the subframes that make the T2 Multiplexed outline (M-outline). These subframes are marked as M1 – M4. 7 T2 M-outlines are then multiplexed to frame a T3 signal. Nonetheless, T3 outlining should be possible through:

M13 Asynchronous Framing

The T3 M-outline is interleaved from 7 multiplexed T2 lines. Every individual line has 85 pieces; 84 pieces of information and a T3 overhead (OH) bit.

C-Bit Parity Framing

At first, C-pieces are bit stuffing pointers for T2 inputs. These are full pieces that are embedded into explicit marks of area in the T2 M-outline. X-pieces are known as Message bits that T3 transmitters depend on to convey nonconcurrent messages with the information. In a C-piece equality outlining sort of T3 line, each C-piece in a T3 outline is utilized for bit stuffing. This network changes the elements of the C-pieces and X-pieces and uses these pieces to oversee highlight point information transmission and furthermore give information joins inside the channels.


Utilization of T3 lines came after the advancement of the T transporter systems during the 1960s. At first, the most minimal T-transporter – T1, was regularly utilized. The principal rendition of the Transmission Carrier system was presented by Bell Systems, which created it in 1962.

This arrangement of information transmission is recognized as one of the main transporters to effectively ship digitized voice transmissions across a network. AT&T began to utilize T1 lines to give better sign quality to intercity connections in 1983 yet the network had effectively been utilizing it in their workplaces during the 1960s. During the 1990s, T3 lines ended up being effective to such an extent that it was utilized as the spine to help the National Science Foundation Network (NSFNET). At present, T3 lines are as yet being used in setting up connections in networks and connections, be that as it may, fresher innovation is currently ready to give quicker and safer network connections.