ISDN 10-20-30

Telstra and Optus ISDN Services

Telstra ISDN and Optus Multiline Are Being Replaced by IP Lines

ISDN (Integrated Services Digital Network) is a digital network technology that can carry voice and data services in a digital format over a standard telephone line. It allows for between 10 and 30 concurrent telephone calls at the same time over the one service connection. For businesses that required more than 30 call lines, multiple ISDN connections were grouped together.
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ISDN lines use the copper network to deliver phone services. In line with the roll-out of NBN and other broadband infrastructure, ISDN is no longer available for new service connections. Commencing September 2019, current services are being gradually disconnected and migrated to IP lines. Business IP lines use SIP (session initiation protocol) to deliver phone lines over the internet.

ISDN Replacement Options

Business IP Lines

Enterprise Grade Business VoIP SIP Trunks from $5 per Month.

Business NetPhones

NBN Ready All-In-One Business VoIP, Hosted PBX and IP Phone.

Hosted PBX Systems

Upgrade to NBN Ready PBX Phone System. Enterprise Grade Features and Functions.


Business VoIP SIP Trunks


Business VoIP and SIP Trunks are the new age business phone lines. If your business has a suitable broadband connection, then you should get connected to the latest technology. Take advantage of enterprise grade features and functions, cheap call rates and low monthly access fees.

Hosted PBX Systems


Hosted PBX is another popular option for businesses that require full PBX functionality with their phone lines. At a fraction of the monthly cost of a PSTN line, you can gain access to all the features and functions of an enterprise grade PBX while taking advantage of much cheaper call rates. You can start with a single extension and build the phone system as your business grows.


Frequently Asked Questions - ISDN

Optus Multiline ISDN 10+ and Telstra ISDN 10/20/30

Both Optus Multiline and Telstra ISDN 10/20/30 were high-performance services that delivered functionality previously reserved for enterprise-sized businesses. Telstra ISDN 10/20/30 was available almost anywhere there was PSTN infrastructure, Optus Multiline was limited to selected areas with Optus infrastructure.
Telstra line rental and additional charges were generally higher than Optus Multiline. In addition, Optus Multiline allowed for services to be scaled in single line increments above the minimum of 10. Telstra only provided ISDN services in blocks of 10. For more information on how to migrate your ISDN services to IP lines please call 1300 000 300 and speak to one of our Business Consultants.
Difference Between ISDN and ISDN2

ISDN 10/20/30 is a primary rate digital service with a maximum capacity of 30 channels (call lines). ISDN2 is a basic rate service with a maximum capacity of 2 channels. Both services deliver digital phone lines with the main difference being capacity and the required PBX functionality. You need a PRI (primary rate interface) card for ISDN and a BRI (basic rate interface) card for ISDN2.

Did You Require an Active Telephone Service to Connect ISDN?

No. The only requirement was that the premises had the necessary PSTN wiring and available capacity. In almost all cases ISDN was delivered using PSTN lines (traditional copper lines) to establish a data link. The premises had to have the required PSTN wiring that wasn't being used for other purposes.

Did You Require a PBX System?

Yes. A PBX phone system with a PRI (primary rate interface) card was required.

Did You Need a Separate Telephone Line for the Fax Machine?

No. The fax number could be incorporated in the ISDN service as long as the PBX system can be configured to do so.

Could You Retain Existing Phone Numbers?

Yes. BusinessCom had Local Number Portability (LNP) agreements with all the major carriers. You could consolidate multiple numbers from across a variety of platforms i.e. PSTN, ISDN 2, etc. into the one ISDN service.

Could I Transfer Services From One ISDN Network to Another?

Yes. You could transfer services between networks including all the DIDs (direct in-dial numbers). When transferring ISDN services from one network to another, a new service was installed and the old one was disconnected. Telstra and Optus operated separate networks which meant both may not have been available at the same premises.

What are Direct In-Dial Numbers?

Direct in-dial numbers are landline numbers attached to the ISDN service. Apart from the main business numbers, consecutive DIDs can be allocated to individual PBX extensions. That way outside callers can dial the extension directly, eliminating the need to go through reception. Direct in-dial numbers are usually available in blocks of 10 and 100 numbers.


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