At a minimum, an enhanced 9-1-1 system implemented in Maryland shall include: Sufficient incoming 9-1-1 lines for each telephone central office to ensure that not more than one in 100 call attempts during the average busy hour is blocked; Connections to all public safety agencies covered by the system; 24 hour, 7 day operation of the public safety answering point staffed with personnel trained as required under this chapter; First priority to answering 9-1-1 calls; Electronic recording of all 9-1-1 calls; Playback capability of all 9-1-1 calls; Connection to adjacent public safety answering points by private lines when there is a telephone exchange and jurisdictional boundary not covered by selective routing; Security measures sufficient to minimize intentional disruption of the operation; Standby emergency electrical power to keep the public safety answering point operating when commercial power fails; At least one administrative line for nonemergency calls; Written operational procedures; Automatic location identification (ALI), which displays, at the public safety answering point, the address or location of the calling instrument; Automatic number identification (ANI), which displays, at the public safety answering point, the calling telephone number; Central office identification used to identify dedicated lines or trunks from a central office when a public safety answering point serves more than one central office; A distinct tone, visible signal, or other process for: Alerting the call taker that an incoming 9-1-1 call was disconnected; and Receiving and displaying the telephone number with ANI and ALI information for a disconnected 9-1-1 call, when available; Providing access to services for an individual: With a speech or hearing disability; or Who does not speak or understand the English language; and Other technical advances approved by the Board.