ISDN2e is BT's high-performance voice and data service for small offices. With a basic installation you can connect up to eight digital devices and make two calls at once. ISDN also offers 64/128k internet access - useful if broadband hasn't yet reached your exchange.
A two-channel ISDN2e circuit costs about the same as two conventional phone lines, but it offers higher quality and far greater potential.
Below is an overview of what ISDN2e is and what you can accomplish with it. Find out more about the calling features and benefits of ISDN2e, and view our troubleshooting guide.
Using ISDN2e, at what speed should I be connecting to the internet?
Normal connection gives a data-rate of 64k. It is possible to double this to 128k by bonding two simultaneous ISDN connections. To do this, your equipment will need correct configuration and your Internet Service Provider (ISP) must support bonded ISDN connections.
While most ISPs accept ISDN connections, standard packages are usually limited to a single 64k channel. If you wish to use bonded 128k channels you should consult your ISP first. If you attempt to connect to your ISP at 128K without the correct set-up, you may see a blank screen or an error message, or the call may fail. You might also incur additional call charges.
What is channel bonding?
Two 64k ISDN2e channels can be bonded to create a digital link that operates at 128k. If you wish to do this when you connect to the internet, you should consult your Internet Service Provider. Bonding is likely to involve reconfiguring your access application, eg, Windows Dial-up Networking. Note that a bonded digital call is charged as two calls.
What happens to a digital connection if I am using both channels and someone picks up the phone?
Unlike an analogue line, the digital connection will be unaffected. However, the person picking up the phone will hear no dial tone and will not be able to make a call.
Can I use a modem with the digital lines?
You cannot plug an analogue modem directly into the ISDN2e box. You can, however, plug a modem lead (e.g. from a laptop computer) into an analogue port on a Terminal Adapter. The modem will connect at its normal speed.
Can I use ISDN2e to connect to a customer or supplier who is using an analogue modem?
That depends on the ISDN interface in your computer. A modern ISDN card should be able to emulate an analogue modem, matching its speed to the modem being dialled. If your equipment supports this feature there should be no difficulty connecting to a remote analogue modem.
Can I get a static IP address with my ISDN2e connection?
Your ISP, not the telephone company, determines the IP address used when you connect to the internet. Some ISPs will allow you to retain the same IP address (known as a static IP) whenever you connect. If you wish to have a static IP, consult your ISP.
I have ISDN2e. Can I add more ISDN channels to it?
Yes. One of the advantages of ISDN2e is that you can add pairs of channels. You can have 2, 4, 6 or 8 channels, all under the same number.
What is the maximum number of channels I can have using ISDN2e?
Each ISDN2e circuit has two channels. Multiple circuits, however, can be combined in a group that shares the same numbers and features.
There is no maximum limit (apart from exchange capacity) to the number of ISDN circuits you can have. If you need eight channels or more, you might reduce costs by moving to the ISDN30 service. This has an entry-level of eight channels.
How can I tell if I have been disconnected from a call?
Most phone systems and Group 4 fax machines clearly indicate call status. To avoid paying for unintentionally extended calls, ensure that you understand the call-status display. Likewise, find out how your ISDN card or Terminal Adapter indicates call status.
What is the line loss limit on ISDN2e?
The line loss for ISDN2e is 47 dB. The exact distance this represents depends on the type of cable, number of joints, etc, between the exchange and your premises. For this reason, ISDN installation is always subject to a preliminary survey.
What signalling type does ISDN2e use?
ISDN2e uses the signalling protocol generically known as Q.931 or Euro-ISDN.
I need to send some alphanumeric characters down the ISDN line, along with the number that I am dialling. Can I do this?
Yes, this is known as sub-addressing. It can be used for calls between ISDN circuits. Sub-addressing allows you to send up to 20 alphanumeric characters (apart from the # symbol) when making a call. ISDN users can allocate different combinations of characters to each device connected to their line, in a similar way to Multiple Subscriber Numbering (MSN). Incoming calls that include the sub-address then go to a precise destination. This might be a device connected to a LAN, individual devices connected to an ISDN2e line, or an application on a host computer.
Before using this service you should check that your terminal equipment can send and/or receive sub addresses. Sub-addressing cannot be used on calls to the PSTN or on International Speech calls. The type and location of the call parties determine the maximum number of sub-address characters that can be used.
Can my alarm system run over my ISDN2e line?
If your alarm system currently relies on a conventional telephone line, you may be able to connect it using an ISDN Terminal Adapter. You will need to check with your alarm company that your system is supported on ISDN connections.