# The Telecommunications (Open Network Provision) (Voice Telephony) Regulations 1998, Part 2


(a) Calling-line identification
i.e. the calling party’s number is presented to the called party prior to the call’s being established.
(b) Direct dialling-in (or facilities offering equivalent functionality)
i.e. users on a private branch exchange (PBX) or similar private system can be called directly from the fixed public telephone system, without the intervention of the PBX attendant.
(c) Call forwarding
i.e. incoming calls sent to another destination in the same or another Member State (for example, on no reply, on busy, or unconditionally).

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Source: https://www.legislation.gov.uk/uksi/1998/1580/schedule/I/part/2 (the official version)
Page: https://openlegislation.uk/telecommunications-open-network-provision-voice-telephony-regulations-1998/schedule-I/part-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.