Attempted to repurpose some daisy-chained CAT5 pulled for phone lines in mid-1990's for use as a T100 data link. Somewhere along one of the runs, Pins 1 and 2 (GW and G) are broken/missing/damaged.  Assuming all other conductors are ok, should this cable work for T100 link?

Can an anyone explain in more detail how each pair is utilized in a T10 vs. T100 vs. T1000?

TIA