; and (2) regardless of whether the user is required to dial a digit, code, prefix, or post-fix described in paragraph (1) for other calls. (d) Other 9–1–1 emergency dialing patterns Nothing in this section shall prohibit the configuration of a multi-line telephone system so that other 9–1–1 emergency dialing patterns will also initiate a call to a public safety answering point, provided that the dialing pattern 9–1–1 remains available to users. (e) On-Site notification (1) In general A person engaged in the business of installing multi-line telephone systems serving locations in the United States, in installing a system described in paragraph (2) in the United States, shall configure the system so that when a person at the facility where the system is installed initiates a call to 9–1–1 using the system, the system provides a notification to— (A) a central location at the facility