Telstra ISDN2 Lines

ISDN2 Phone Lines Being Replaced by IP Lines

ISDN2 is an ISDN (Integrated Services Digital Network) service that allowed for two concurrent telephone calls at the same time over the one PSTN line. ISDN2 services provided  clear, high-quality telephone connections, and offered more call and messaging features than standard PSTN business lines. The service was usually suited to businesses that required 2 to 6 telephone lines.
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ISDN2 lines use the copper network to deliver phone services. In line with the roll-out of NBN and other broadband infrastructure, ISDN2 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.

ISDN2 Replacement Options

Business NetPhones

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

Business VoIP Lines

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

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 - ISDN2

Difference Between ISDN2 and ISDN

Although they're both a type of ISDN (Integrated Services Digital Network) technology, there are 2 main differences.

Number of Channels

As the name indicates, the number of channels (call lines) available with ISDN2 is two. Multiple services are bundled together to deliver more than two lines (in multiples of 2). With ISDN, there is a minimum number of 10 channels and a maximum of 30.

PBX Equipment

ISDN is a primary rate digital service that requires the PBX to be fitted with a PRI (primary rate interface) card. ISDN2 is a basic rate service that requires the PBX to be fitted with a BRI )basic rate interface) card.

Do I Require an Active PSTN Service to Connect ISDN2?

No. The only requirement is for the business premises to have the necessary PSTN wiring and capacity.

Traditional copper lines are required to deliver ISDN2. There is no need to have an active PSTN line but there must be the required PSTN wiring not being used for other purposes.

Do I Require a PBX System to Operate ISDN2 Lines?

Yes. And the phone system must be fitted with a BRI (basic rate interface) card.

Most SME PBX systems can be used for both ISDN and ISDN2. However, they must be fitted with the necessary interface card, which is different for both technologies. To find out is your system is compatible, either check with your PBX maintainer or call us on 1300 000 300.

Can an ISDN2 Line Be Used as a Fax Line?

Yes. However, it's dependent upon your telephone system and if it can be programmed to route fax calls to the fax machine. Please consult your PBX technician.

One of the best ways to overcome having to allocate a phone line to a fax facility is transferring to a Virtual Fax Service. It utilises fax2email and email2fax, eliminating the need to have a physical fax machine or a dedicated phone line.

Can I Retain My Existing Numbers?

Yes. BusinessCom has LNP (local number portability) arrangements with all major carriers.

When upgrading from a PSTN service, your main business number will be made part of the ISDN2 service. Please note that only your main business number will be retained. When switching your existing ISDN2 lines to BusinessCom, all your existing numbers will be retained.

Transferring Existing ISDN2 Services to BusinessCom

The ISDN2 network is wholly owned by Telstra, a wholesale provider of BusinessCom. When transferring services, there are no network changes and it's only the billing that gets transferred.

Transferring your existing service to BusinessCom is seamless. All of your existing features and configuration remains as is and you won't even notice when the changeover happens.


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