This article is from the Data Communications Cabling FAQ, by Peter Macaulay pmac@fox.nstn.ca with numerous contributions by others.
With reference to T568B above;
ATM 155Mbps uses pairs 2 and 4 (pins 1-2, 7-8)
Ethernet 10Base-T uses pairs 2 and 3 (pins 1-2, 3-6)
Ethernet 100Base-T4 uses pairs 2 and 3 (4T+) (pins 1-2, 3-6)
Ethernet 100Base-T8 uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)
Token-Ring uses pairs 1 and 3 (pins 4-5, 3-6)
TP-PMD uses pairs 2 and 4 (pins 1-2, 7-8)
100VG-AnyLAN uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)
 
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