T-carrier, is the generic designator for any of several digitally multiplexed telecommunications carrier systems developed by AT&T Bell Labs in 1957.

Frequency
Voice band (0.3 - 3.4 KHz)

Signal
Digital

Line Code
AMI, B8ZS, HDB3
Mark : 3.0V dc
Space : 0V dc +/-0.30V dc
Pulse Width : 648 ns +/- 15 ns

Modulation
Pulse Code Modulation(PCM)

Multiplexing
Time Division Multiplexing(TDM)

Transmission Direction
Full Duplex

Transmission Mode
Synchronous

Medium
Unsheilded Twisted Pair
24 AWG, 100 ohms impedance @ .772 MHz, 7 dB attenuation/ 1000 ft @ .772 MHz, 41 dB crosst per 1000 ft.
As Per Rs-568 - Level 1 & Level 2 type cable

Cabling
Co-directional 4 Wires

Connectors

Subminiature 15 female

1	Send Data (tip)
2	Reserved for network
3	Receive Data (tip)
4	Reserved for network
5	Not defined
6	Not defined
7	Not defined
8	Not Defined
9	Send Data (ring)
10	No connect
11	Receive Data (ring)
12	No connect
13	No Connect
14	No connect
15	No connect

mini-modular 8 pin

1	Transmit (ring)
2	Not Used
3	Not Used
4	Receive (ring)
5	Receive (tip)
6	Not Used
7	Not Used
8	Transmit (tip)

RJ-48

1	Receive (ring)
2	Receive (tip)
3	Not Used
4	Transmit (ring)
5	Transmit (tip)
6	Not Used
7	Not Used
8	Not Used

T-Carrier Heirarchy

Carrier	Signal Level	No.Of T1 Signals	Voice Channels	Speed
	DS-0	1/24	1	0.064 mbps
T1	DS-1	1	24	1.544 mbps
T1c	DS-1c	2	48	3.152 mbps
T2	DS-2	4	96	6.176 mbps
T3	DS-3	28	672	44.736 mbps
T3c	DS-3c	56	1344	89.472 mbps
T4	DS-4	168	4032	274.176mbps

T1 Frame Structure

Super Frame



Extended Super Frame