sentences:  This option allows companies, such as cable television, wireless providers, and electric/gas utilities, who already have customers, installation and maintenance crews, and billing systems, to lease the network elements they are missing, such as voice switches or electronic ordering systems, to complete their local telephone system.The 1996 Act, thus mandates that the traditional vertical hierarchy of the telephone industry be divided into parts, known as Unbundled Network Elements (UNE), so that competitive new entrants can choose what they need to provide competitive local telecommunications service.In the United Kingdom, Downstream access (DSA) was first introduced in 2003.