TMnet ISDN Guide Ver 0.3

Foreword

This guide is intended as an introduction to ISDN as it applies to TMnet Support and Telekom Malaysia. It covers the following topics:

ISDN Introduction

ISDN stands for Integrated Services Digital Network. It offers the following benefits to the customer:

However ISDN has the following shortcomings

How ISDN works

ISDN is very different from normal PSTN phone lines.

A normal PSTN phone line uses sound to transmit information, be it voice or data, over copper cables to the nearest exchange. The quality of the sound is dependent on the condition of the copper cable, the distance from the exchange and so on. PSTN was never designed for data transmission, and so modems are needed for sound-to-electrical signal conversion (analog to digital) conversion.

ISDN however, uses digital signals to transmit information, be it voice or data, over copper cables to the nearest exchange. Since the entire transmission channel is digital, it is much faster and no analog to digital conversion takes place. It is also very tolerant of line quality and not subject to unexpected disconnections.

Please examine the diagram below to compare ISDN and PSTN.

Even though ISDN runs on standard pair of copper wires, there are 3 virtual channels available to you:

You may use one or both B channels for voice or data. Even though ISDN lines are digital, ISDN equipment normally have one or 2 ports to allow you to connect analog telecommunications devices such as phones, faxes and modems. Some ISDN phones even allow you to use all 3 channels for voice connections, although not simultaneously.

You can configure your ISDN equipment to connect to the Internet using both B channels simultaneously. This is called Multilink PPP, and it allows data transfer rates of up to 128kpbs.

ISDN Line Application

You may apply for an ISDN line at selected Kedai Telekom. Please note that ISDN service may not be available in all areas, due to technical reasons.

The list of selected Kedai Telekom and other pre-sale information is given here (http://www.tm.net.my/isdn.htm).

First you need to get the form from the front counter.

Fill in your details in Section 1. For personal users, place your name as the Name of Company. Other fields that need to be filled are Installation address, Post code, Contact person and Telephone number.

Under Section 2, you need to fill in the following information:

Under Section 2B - Type of Equipment (CPE) to be connected, you need to tick the Terminal Adapter and Internet Access boxes.

When the form is complete, submit it to the clerk in charge. You can choose to be billed for installation when the first monthly bill arrives.

ISDN Line Installation

You may choose to convert your existing line to ISDN, or you may specify a completely new installation. If you choose to do the latter, you have to engage a Telekom contractor (list available at Kedai Telekom) to install the line for you, and you will be charged for the service.

In any case, when the Telekom Malaysia CNO arrives, he will do the following:

The type of NT you get is dependent upon which exchange you are connected to.Telekom Malaysia uses Ericsson, Fujitsu, Motorola or NEC NTs. If you are not sure which type of NT you are using, please ask the CNO. You need this information when reporting a fault to Telekom Malaysia's Fault Reporting Service.

You will need a power source for this NT at all times. The interface between the NT and the phone cable is known as the U interface.

After testing the line, the CNO's job is complete. The next step should be performed by a computer vendor.

ISDN Terminal Adapter Installation

To connect your computer to the NT, you need to use an ISDN Terminal Adapter (TA) or ISDN Router. The connection between the ISDN TA or Router and the NT is knows as the S/T interface. Normally the NT has two S/T interfaces, the other one will be used by Telekom Malaysia CNOs for testing purposes.

Some NTs, like the NEC NT shown here, have only one S/T interface.The other port is the connection to the U interface.

Sometimes ISDN TAs are referred to as ISDN modems. This is actually incorrect since no analog to digital conversion takes place.

There are internal and external models available. Internal ISDN TAs are installed into one of your computer's slots. External ISDN TAs are typically connected to your computer's serial port.

ISDN TAs have to be configured before being used. For best results, configuration must be done by the Vendor. The configurations involves setting the NT type, enabling MultilinkPPP, assigning phone numbers to analog ports and so on.

Once this configuration is complete, the TA may be treated just like an analog modem. It is controlled by standard dialler software, such as Win95 DUN (Win95) or FreePPP (Mac). Win95 and Mac configuration is almost the same as Dial 1515 except:

Even though you can achieve rates of 128kpbs, the serial port on most PCs are limited to 115kpbs. You will need a different serial card to achieve higher port speeds. Most new Macs, however, can support 230kpbs as is.

Some TAs come with a built-in NT. These TAs may be connected straight to the U interface, however this is not recommended as Telekom Malaysia will not be able to guarantee network connectivity. Always try to obtain TAs with S/T interfaces instead.

Most TAs have lights on them. However not all the lights are standard. Here is the lights for the TA I tested:

The ports on TAs also differ from TA to TA. Here are the ports for the TA I tested:

Please see the section on ISDN configurations for more information.

ISDN Router Installation

If you wish to connect a network of computers to the NT, you need to use an ISDN Router. The connection between the Router and the NT is knows as the S/T interface. Normally the NT has two S/T interfaces, the other one will be used by Telekom Malaysia CNOs for testing purposes.

ISDN Routers are typically connected to a network hub via RJ45 Ethernet cables. You may also connect a single computer to a Router by using an Ethernet cross cable (which enables you to utilise to full speed of the ISDN line, since you are no longer limited by your serial port speed.)

ISDN Routers have to be configured before being used. For best results, configuration must be done by the Vendor. The configurations involves setting the IP address of the router (usually set to 200.200.200.201), NT type, enabling MultilinkPPP, routing phone numbers to analog ports and so on. Once this configuration is complete, the TA may be treated just like an router. Username and password for Internet services are stored in the Router and not the computers connected to it. You need to use the Network Control Panel (Win95) or TCP/IP (Mac) to set the router as your internet gateway. The IP addresses will be something like 200.200.200.202, 203, and so on. Note that these IP addresses only exist behind the ISDN Router and not seen outside, so some Internet services such as ICQ may not work.

Some Routers come with a built-in NT. These TAs may be connected straight to the U interface, however this is not recommended as Telekom Malaysia will not be able to guarantee network connectivity. Always try to get Routers with S/T interfaces instead.

Most Routers have lights on them. However not all the lights are standard. Here is the lights for the Router I tested:

The ports on Routers also differ from Router to router.. Here are the ports for the Router I tested:

ISDN configurations

A typical ISDN TA installation is shown here. Note that the Network Terminator also requires a power supply.

A Typical ISDN Router installation for one computer via Ethernet cross cable is shown here.

Actual photo of a similar configuration to that shown above. No analog devices are connected. The Cross cable is red.The black box is the NT's power supply and grounding terminal. The ISDN router's power supply is not in the picture.

A typical ISDN Router installation to a computer network is shown here.

Problems Encountered During Testing

These are problems I encountered after approximately one month of testing with a 3Com Impact TA. Review unit courtesy Micro Village, 03 - 705 1686.

Cause:
D channnel is only used to set up the line. After that, it is no longer used.

Solution:
If you have an analog phone connected to the TA, pick up the receiver and the D channel will reactivate.

Cause:
Many possible causes, but normally can only be fixed by a vendor or Telekom Malaysia.

Solution:
Please check to see if you can still make voice calls. If you can't, you need to report the fault to Telekom Malaysia's Fault Reporting Service. Dial 100 and inform them of your name, phone number and type of NT.

If you can make voice calls, chances are your line is OK, but your TA is faulty. Inform the TA vendor.

If your TA is fine, check your username and password with TMnet Support.

Cause:
This happens when Multilink PPP is enabled and only one B channel is authenticated.

Solution:
Disconnect and reconnect again. You may have to do this a few times to connect successfully.

Cause:
This happens during when you are connected and there is no activity.

Workaround:
Start a file download. As long as the file is being downloaded (there is activity), you will not be disconnected.

Cause:
This is due to the fact the the FTP server will perform reverse lookups to confirm identity and will disallow transactions if reverse lookup fails.

Solution:
Please inform TMnet Support of this matter, and we will forward it to the proper department.

Cause:
Improper disconnection, such as shutting down the computer while connected.

Solution:
Reset the ISDN TA. You can do this by switching it off and on again, or pressing the reset button.

Cause:
Incorrect TA configuration

Solution:
Ask the vendor to reconfigure the ISDN TA.

Cause:
Incorrect TA configuration

Solution:
Ask the vendor to reconfigure the ISDN TA.

Cause:
Faulty NT.

Solution:
Ericcson NTs have 2 lights, Power and Line. If only the Power light is on, the NT is faulty. Motorola NTs typically have 2 lights on. If only one light is on, the NT is faulty.

Call Telekom Malaysia Fault Reporting Service by dialling 100. Give your particulars and the type of NT you are using. Telekom Malaysia CNO will replace your NT and/or troubleshoot your line.

Contact Information

For sales and marketing information, please fax 03-7038665 (Attn: Marketing Dept.) and for any ISDN information please fax 03-7042204, (Attn: Corporate Technical Support).

If you have problems with the line, up to and including the NT, please contact Telekom Malaysia's Fault Reporting Service by dialling 100.

If you have problems with any of the following, please contact the ISDN Vendor.

If you require Technical Support, please call 1-800-88-INET (1-800-88-4638) or fax 03-704 2204/03 704 2885. Technical Support's responsibility is the following: