ISDN30 Beginners Guide

ISDN30 Beginners Guide




ISDN 30 is a dominant rate service. It is obtainable in DASS, I.421 and ISDN30e versions. ISDN30 DASS. ISDN 30 (DASS 2) conforms to BT’s own standard (see I.421 for Euro version). ISDN 30 is the equivalent of up to 30 exchange lines (Channels) delivered to the customer’s premises and connected to a PBX (such a Mitel 3300 phone system) or for data applications to PC or multiplexor such as the BT Jtec.

ISDN 30 (DASS 2) is obtainable from only 8 channels upwards and consequently applicable to customers of all sizes. ISDN 30 (DASS 2) is provided typically over fiber cable but can be provided over transverse screen, Microwave or copper pairs. Each system is a 2Mbit/s digital connection from the BT exchange presented as a G703 BNC connector. 

ISDN30(I.421)

ISDN30(I.421) is the European standard for digital connection to ISDN dominant rate service. This uses the Q931 signaling protocol, meeting the European Telecom Standards Institute (ETSI) specification, which conforms to the ITU-T (before known as CCITT) standards.

ISDN30(I.421) is the equivalent of up to 30 exchange lines (known as Channels) delivered to the customer’s premises and connected to an iSPBX or for data applications to a PC or multiplexer. It is obtainable from only 8 channels upward and consequently applicable to all sizes of customer.

ISDN30(I.421) is provided typically over fibre cable but can be provided over transverse screen, microwave or copper pairs. Each system is a 2Mbit/s digital connection from the BT exchange presented as an RJ45 connector.

ISDN30e

ISDN30e an enhancement to the ISDN 30(I.421) service.  ISDN 30e is provided with the latest network software, which provides customers with access to Supplementary sets such as; Call Forwarding of Voice and Data calls. ISDN 30e will also permit the provision of new sets in the future such as Customer Controlled Call Forwarding.

Existing ISDN 30 (I.421) customer installations will be unaffected and will not be automatically enhanced. ISDN 30e is provided over fibre, transverse screen or copper. Each system is a 2Mbit/s digital connection from an exchange presented as an RJ45 connector. ISDN 30e uses the Q931 signaling protocol, and meets European Telecom Standards Institute (ETSI) specifications. Enhancement to the ISDN 30e service is free of charge for ISDN 30(I.421) customers. For ISDN 30(DASS) customers, there is a charge for upgrading to ISDN 30e.

Main changes between DASS and ISDN 30e/ISDN 30(I.421) are:

  • Signaling For the ISDN 30e/ISDN 30(I.421) service DASS 2 signaling is replaced with Q931 signaling to the ETSI standard.
  • A new NTE For the ISDN 30e/ISDN 30(I.421) service the interface connector for the ISDN 30 (DASS 2) BNC 75Ohm Unbalanced (G703) is replaced with an I.421 socket, EN28877 (RJ45) 120-Ohm Balanced connector to the CCITT I.421 standard.

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