atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Can a noob do inside wiring for T1?

I was looking over some pinout charts, and noticed that the RJ-48C seems to be the same as the RJ-48X jack except for the shorting bars. It says here that both of those jacks are for 1.544 Mbps data service. Where would you use the RJ-48C (without the shorting bars) instead of the RJ-48X (with the shorting bars)?

Is "1.544 Mbps data service" always a T1 or PRI line, or is there some other 1.544 Mbps data service out there?