The RJ-45 connector is an 8pin, unshielded twisted pair Ethernet connection components used to connect your computer to a network. The term unshielded, "twisted" refers to its configuration to cancel out electromagnetic interference; its max distance for data transfer is 100 meters. The RJ11 connector is a 6pin connector which uses only two of its wires for data transfer. If you are connecting to a traditional phone line into a modem or fax, you are using an RJ11. The two connectors are not interchangeable connection types.