双绞线分两类:屏蔽双绞线和非屏蔽双绞线。普通的电话线就是非屏蔽双绞线。它也使用于局域网,晚于加工和安装。非屏蔽双绞线有EIA-568-A和EIA-568-B两个标准,由电子工业布线标准颁布的。 Twisted pair comes in two varieties: unshielded and .Unshielded twisted pair(UTP) is ordinary telephone .It is also used for local area and is easy to work and install.