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Using ISDN30/30e | BT Business
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Using ISDN30/30e

For more information on ISDN30 and ISDN30e, go to our ISDN30/30e guide.

ISDN30e User Guide

For more information on ISDN30e, please view the user guide:

ISDN30e User Guide (PDF, 106KB)

You may need Adobe Acrobat reader.

Alternative and diverse routing

Alternative routing provides two different cables from the local exchange to your site, so you can protect against cable failure as your service will be maintained on the alternative route.

With diverse routing, you can protect not only against cable failure but also against local exchange failure as there are two separate routes from two exchanges to your site.

Customer Controlled Call Forwarding / Diversion options

Customer Controlled Call Forwarding diverts calls to all numbers to a single number of your choosing. This call-forwarding option is applied by you by programming your equipment to divert the calls. This means it’s exchange-independent. Contact your equipment manufacturers if you’re not sure whether your equipment supports the service. To enable call forwarding on the line, ring ISDN30/30e Business Sales.

Speech only or 3.1Khz calls can be forwarded to the PSTN. After the initial diversion, a call can be forwarded repeatedly up to a total of 4 times.

The forwarded leg of the call is chargeable. The charges appear on your bill along with the subscription for the forwarding service.

The following options are available when you use this type of forwarding:

  • Call Forwarding / Diversion Unconditional (CFU)
    All incoming calls are immediately forwarded to the nominated destination number.
  • Call Forwarding / Diversion on No Reply (CFNR)
    All calls are forwarded to the nominated destination number if the call is not answered within approximately 20 seconds
  • Call Forwarding on Busy (CFB) / Call Divert on Engaged and Failure on DASS
    All calls are forwarded to the nominated destination number if the line is engaged.


Admin Provided Call Forwarding / Diversion options

Admin Provided Call Forwarding / Call Diversion is an exchange-controlled call forwarding option. This means that it doesn’t require special equipment.

To set up this service call ISDN30/30e Business Sales where you can specify the destination number to which you want calls to be forwarded. The service becomes active within 24 hours.

Calls can be forwarded to PSTN, ISDN2e, ISDN30/30e (speech only or 3.1Khz can be forwarded to the PSTN). After the initial diversion, a call can be forwarded repeatedly up to a total of 4 times.

The following options are available with this type of forwarding:

  • Call Forwarding / Diversion Unconditional (CFU)
    All incoming calls are immediately forwarded to the nominated destination number.
  • Call Forwarding / Diversion on No Reply (CFNR)
    The service automatically forwards all incoming calls to the nominated destination number if the customer does not answer the call within approximately 20 seconds.
  • Call Forwarding on Busy (CFB) / Call Divert on Engaged and Failure on DASS
    The service automatically forwards all incoming calls (voice and data) to the nominated number if the customer is already engaged (also if circuit fails on DASS setups). The forwarding takes place when either all channels are in use or when an individual called number is busy (CPE supplies a ‘User Determined Busy’ signal to the network).

Maintenance options available on ISDN30

Our Prompt Care package is provided as part of the ISDN30 service.

Package Engineer Visit Days Engineer Visit Hours Response Time BT aims to fix faults by -
Prompt Monday to Saturday (excluding Bank and Public Holidays) Mon - Sat 8am till 6pm 4 Hours* End of the next working day
Total 7 days a week Mon-Fri 07:00-21:00 and Saturday to Sunday including Bank Holidays 08:00-18:00 4 Hours* Within 24 hours

*Response qualifies as a confirmation that the fault is accepted and the provision of a fault reference number.

If you’d like to upgrade to the Total Care package just contact us and we’ll do it for you. 


BT ISDN30 Business Continuity 

BT ISDN30 Business Continuity options allow you to minimise the impacts of fire, flood or storm or human error by delivering your connection in a number of different ways. This ensures that in the event of a service failure, the service impact is kept to a minimum.

Find out what options are available:

Resilience options  

Your ISDN30/30e connection can be delivered in a number of different ways to make sure that in the unlikely event of a failure, such as a JCB damaging your line, service impact is kept to a minimum.

Standard connection and rental charges apply for standby lines served from the same exchange as your primary site. If you need the standby lines to be serviced via a different exchange, out of area charges will apply in addition to connection and rental charges.

1. Back in Business - Single Site

  • calls are diverted to a BT Managed Call Centre
  • customer calls pre-allocated BT number to request service
  • suitable for customers with fewer than 30 channels.

2. Alternate Routing

ISDN30/30e can be routed via separate cables from the serving exchange. There are two options:

  • separate cables, same ducting
  • separate cables, separate ducting.

3. Diverse Routing

The service is provided via two different cables from two different serving exchanges. In the very unlikely event of a cable failure and a problem at the exchange, the chance of a complete loss of service is reduced. Separate DDI groups are served by the two exchanges.

4. Dual Parenting

The same DDI numbers are served from two different exchanges. This means that in the unlikely event of a problem with one of the exchanges, calls can still get through. Dual Parenting can be provided in one of two ways:

  • Option 1 uses two different exchanges and connects the ISDN 30 service via Diverse Routing.
  • Option 2 connects your site to the local exchange via two ISDN 30 bearers provided using the same duct and cabling. Once at that exchange, however, half the calls are diverted via the BT network to the next nearest exchange and alternative processor.

5. ISDN30/30e Site Assurance

Again, there are two possible options:

  • Option 1, 'Back in Business Multi-Site', uses Call Diversion for ISDN30 (DASS2) or Call Forwarding for ISDN30e services. Should a problem at your primary site occur, voice calls for ISDN30 (DASS2), and voice and data calls for ISDN30e, are diverted to a pre-arranged single number. On a request being received, the changeover to the standby site usually takes place within 30 minutes per bearer. You will be charged for the diverted leg of the call with this option.
  • Option 2 is delivered by providing a group of ISDN30 lines to your standby site. These lines are provided with a status of 'out of service'. If a problem occurs at your primary site, at your request, primary site lines are adjusted to 'out of service' mode and standby lines are brought into service. The back-up lines allow DDI, voice, and data calls for both ISDN30 (DASS2) and ISDN30e to be mapped across to your back-up site.
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