scope:

This European Telecommunication Standard (ETS) specifies the transmission requirements for digital Private Branch eXchanges (PBXs) (through-connecting telecommunications equipment) that:

- are not part of the public network;

- carry 3,1 kHz telephony between analogue interfaces, digital interfaces carrying 64 kbit/s A-law encoded signals and the acoustic interfaces of handset telephony terminals that are designed to be used together with the PBX for connections involving digital access to the public switched network;

- are capable of providing, for the purposes of testing, a test point that offers a 64 kbit/s - signal with bit integrity to the digital transmission path (this test point need not be provided in production versions of a PBX).

NOTE: When dealing with voice bandwidth data transmission, special consideration may have to be given to certain parameters e.g. group delay distortion, error performance, bit integrity, bit sequence independence (the list is not exhaustive).

This ETS applies to PBXs that carry 3,1 kHz voice telephony, irrespective of whether they carry other services in addition.

This ETS does not apply to:

- cordless interfaces or digital interfaces carrying signals coded using other coding laws;

- the transmission of services other than 3,1 kHz voice telephony; and

- handsfree and loudspeaking telephony terminals.