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T-Carriers T1, T2, and T3

I have a question about T1, T2 and T3 network connections.

I understand that ISDN PRI can provide speeds up to T1 on copper telephone lines, but are T2, and T3 provided over special media? What type of media is used at Layer 1 on the OSI model?

Thank you


Re: T-Carriers T1, T2, and T3


First of all PRI is a type of T1, you can have T1 which is not PRI, its all about coding and modulating.

A T3 for example is delivered native on a copper Trunk. T3 may be converted to a fiber run when needing longer distances between termination points. When delivering data over an OC3 or greater SONET (using fiber rather than copper) is used. SONET is much faster and has a much lower bit error rate.

NOTE: the DS notation is equivalent to the T notation with DS1 equivalent to T1.

You can check this link it is great:

HTH, please do rate all helpful replies using the scroll box on the right,

Mohammed Mahmoud.