Ideal as a flexible, reliable and single voice and data access connection.

ISDN (Integrated Subscriber Digital Network) provides a high-capacity, direct connection to Spark’s Public Switched Telephone (PSTN) network.

Our ISDN is offered as a Basic Access Rate (BRA) service and is commonly used for connecting trunks to PABXs.  It is particularly suited to regional offices, small businesses and individual users who wish to combine voice and data networking into a single, high-quality access.

Simple and easy to install, it gives your customers the flexibility to control the way their ISDN line is used at any one time - and will cater to their bandwidth-hungry applications and high-speed calling needs.

Our ISDN as a Primary Rate Access (PRA) provides up to 30 channels per link for PABX trunk connection, however, it is no longer available to new end-users.  Our high-quality SIP Trunking service replaces this.

Why Spark ISDN?

Our ISDN BRA service is available throughout New Zealand and offers simultaneous connections in any combination of voice, data or video communications. 

As it is delivered over a single physical connection, it provides you with a cost-effective way to service your customers’ connectivity needs.

Your customer’s will enjoy high speeds and greater performance with a dialled point-to-point data link powered by Spark’s reputable PSTN. 


Key features

  • Connects small to medium PABXs to Spark’s PSTN
  • High-speed, internet access
  • Supports voice, data or video communications
  • Two 64Kbs B channels plus 16Kbs D channel
  • Data access size up to 128Kbps
  • Delivered via copper
  • Capacity for eight devices with separate directory numbers
  • Simultaneous calling on two devices
  • Remote dial-up access to Local Area Network (LAN)
  • Optional smartphone features
  • Supports organic growth
  • e-billing


How it works

Our ISDN service is a Basic Rate Access (BRA) service providing two 64 kbit/s B voice channels into end-users Service Delivery Point (SDP) at their premises over their existing telephone line. 

There is also a 16kbit/s D channel for call setup, signalling and D channel packet access. 

These channels are used to transmit voice, data or video calls. 

Both channels terminate on a Network Terminator (NT).  The NT can be either a Standard NT and/or an NT Plus which contains two ordinary telephone sockets for telephones or fax.  The wiring extending from the NT into the end-user’s premises is called the S/T Bus cabling.

Up to eight devices, such as faxes, printers, telephones or computers can be connected through a single connection and any two devices can have simultaneous calls at the same time.

One directory number comes as standard but up to eight numbers can be provided using the Multiple Subscriber Number Service.

Smartphone services can be incorporated to increase end-user functionality.

While we manage the pricing and contractual arrangements for this service, Chorus will manage the provisioning, billing and any fault resolution required.

It’s easy to set up a new installation as well as re-assign an existing line from another provider. 

Your customer pays a monthly rental charge for their ISDN line as well as any call usage, including local calls.

ISDN BRA lines are first installed as standard business lines, and then converted to BRA lines.

Standard business line installation and conversion fees apply.

Key benefits


Intergrated access

Simplify resources with a single access for voice, data or video communications and choose how your ISDN line is used at any one time.

High-quality links

Consume voice, data and video communications with greater speed thanks to a dialled, point-to-point data link to Spark’s reputable PSTN.

Device connections

Connect up to eight devices such as telephones, faxes, computers or printers, with two devices able to make and/or receive calls at the same time.

Fast install

Get going fast with a discreetly-sized Network Terminating Unit (NTU) that is placed on a desk or mounted on a wall.

Adaptive service

Lease a circuit backup or more bandwidth to meet growing demand and incorporate smartphone services to provide more end-user functionality.

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