This analog signal is then transmitted to the telephone at the receiving end. An enhancement allows digital devices to be located at both ends of telephone communication. This allows several distinct signals to be transmitted simultaneously and greater bandwidth for communications. This essentially means, if verified, that a national dial up telephone tapping capacity has been engineered into the ISDN system from the start. Modern communications systems are virtually transparent to the advanced interceptions equipment which can be used to listen in.
Some systems even lend themselves to a dual role as a national interceptions network.
This allows digital devices, e.g. fax to share the system with existing lines. This effectively means that a national dial up telephone tapping capacity is built into these systems from the start. Enter keywords below.