The Telecommunications (Voice Telephony) Regulations 1997

2.1    Types of connection to the relevant Licensee’s public fixed telephone network

Technical characteristics of interfaces at commonly provided network termination points are required, including where applicable reference to the VTD standards:

• for analogue and/or digitally presented networks:

  (a)

  single line interface;

  (b)

  multi-line interface;

  (c)

  direct dialling-in (DDI) interface;

  (d)

  other interfaces commonly provided,

• for ISDN:

  (a)

  specification of basic and primary rate interfaces at the S/T reference points, including the signalling protocol;

  (b)

  details of bearer services able to carry voice telephony services;

  (c)

  other interfaces commonly provided,

• and any other interfaces commonly provided.

• In addition to the above information to be published on a regular basis in the manner laid down in Condition VTD2.4, the relevant Licensee must inform terminal equipment suppliers, without undue delay, of any particular network characteristics which affect the correct operation of approved terminal equipment.