HP ProBook 6455b, 6555b, 6450b and 6550b Notebook PCs Maintenance and Service Guide

RJ-45 (network)
Pin Signal
1 Transmit +
2 Transmit -
3Receive +
4Unused
5Unused
6Receive -
7Unused
8Unused
RJ-11 (modem)
Pin Signal
1 Unused
2Tip
3Ring
4 Unused
5 Unused
6 Unused
184 Chapter 8 Connector pin assignments