This is relevant: https://www.ad-net.com.tw/what-is-t1-and-e1-difference-between-t1-and-e1-exp... In particular:
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 balanced physical delivery has 4 copper wires. It is similar to that of T1. Whereas in the unbalanced physical delivery there is a coax connector which has one cable for RX and one cable for TX.
As a Stateside person my T1's were all 2 pair wires (going back to the early 90s). It's fair to note that POTs lines are also technically 2 pair... but only one pair was used (their was a push in the 70's to wire up the second line for teens). That said, T1's also historically required a regenerator/repeater every 1000 feet. This is a bigger consideration then the copper in my mind. Further complicating this, much like "ethernet" "T1" is a delivery standard. It turns out that for the better part of 30 years "T1" is actually shipped over a variant of SDSL, and only turned into classic T1 at the DMARC. On 1026, James Knott wrote:
On 10/26/2018 02:42 PM, Carlos E. R. wrote:
Yes, but a T1 was a coaxial cable, designed to carry that speed, whereas a telephone copper pair was designed, if it was at all designed, to carry voice.
Nope, two twisted pairs. The same sort of pairs as used for analog telephone carriers.
BTW, my background is in telecom and I have worked a lot with them over the years.
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