T-carrier
1. The generic designator for any of several digitally multiplexed telecommunications carrier systems.
Note 1: The designators for T-carrier in the North American digital hierarchy correspond to the designators for the digital signal (DS) level hierarchy. See the associated table below.
Note 2: T-carrier systems were originally designed to transmit digitized voice signals. Current applications also include digital data transmission.
Note 3: If an “F” precedes the “T”, a fiber optic cable system is indicated at the same rates.
Note 4: The table below lists the designators and rates for current T-Carrier systems.
Note 5: The North American and Japanese hierarchies are based on multiplexing 24 voice-frequency channels and multiples thereof, whereas the European hierarchy is based on multiplexing 30 voice-frequency channels and multiples thereof. See table below.
T-Carrier Systems
North American
Japanese
European (CEPT)
Level zero (Channel data rate)
64 kb/s (DS0)
64 kb/s
64 kb/s
First level
1. 544 Mb/s (DS1) (24 user channels)
1. 544Mb/s (24 user channels)
2. 048 Mb/s (30 user channels)
(Intermediate level, North American Hierarchy only)
3. 152 Mb/s (DS1C) (48 Ch. )
–
–
Second level
6. 312 Mb/s (DS2) (96 Ch. )
6. 312 Mb/s (96 Ch. ), or
7. 786 Mb/s (120 Ch. )
8. 448 Mb/s (120 Ch. )
Third level
4
4. 736 Mb/s (DS3) (672 Ch. )
3
2. 064 Mb/s (480 Ch. )
3
4. 368 Mb/s (480 Ch. )
Fourth level
27
4. 176 Mb/s (DS4) (4032 Ch. )
9
7. 728 Mb/s (1440 Ch. )
13
9. 268 Mb/s (1920 Ch. )
Fifth level
40
0. 352 Mb/s (5760 Ch. )
56
5. 148 Mb/s (7680 Ch. )
56
5. 148 Mb/s (7680 Ch. )
Note 1: The DS designations are used in connection with the North American hierarchy only. Note 2: There are other data rates in use, e.g., military systems that operate at six and eight times the DS1 rate. At least one manufacturer has a commercial system that operates at 90 Mb/s, twice the DS3 rate. New systems, which take advantage of the high data rates offered by optical communications links, are also deployed or are under development.