Types of telephone lines

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How do telephone lines & calls work?

One needs to understand, that only one telephone call can be made or received, per telephone line. Multiple telephone lines are thus required to receive & make simultaneous calls.

How to determine the type of telephone lines you need         

If you have an existing PABX, but are not sure what type of telephone lines exist on it, you should be able to find this information on your Telkom account under the telephony detail section which is normally at the top of the 3rd page (5th page number). 

The following explains how telephone lines normally appear on a Telkom telephone account:       
Analogue switchboard lines        - Junction lines
ISDN switchboard lines              - ISDN BRI
PRI switchboard lines                - ISDN PRI

Any lines not connected to a PABX (such as fax lines), are normally shown as ‘Your Line (s)’.

Analogue telephone lines

These are your traditional telephone lines.
Even though they are analogue, they work very effectively they work very effectively and are the
most common PABX telephone lines in use in South Africa.

ISDN telephone lines

These are digital telephone lines with each ISDN line consisting of two channels, allowing two telephone calls to be made simultaneously. ISDN lines are also called Basic Rate ISDN (BRI).

Direct Dialing In (DDI) is the most significant feature of ISDN lines. DDI allows outside callers to dial directly through to internal extension users, thereby relieving a busy receptionist from having to answer the call first. DDI numbers are available in packets of 20.

Normally, if one converts existing analogue telephone lines to ISDN telephone lines in order to make use of the DDI feature, your main analogue telephone number will change. We do however, have a solution which will allow you to keep your main telephone number and still have DDI on your new ISDN telephone lines. Discuss this with us.

It is not always cost effective to add ISDN telephone lines on small PABX’s because  ISDN PABX cards for these smaller configurations are slightly more expensive. We recommend that you consider making use of ISDN telephone lines if you require six or more telephone lines on your PABX.

PRI telephone lines

These are ISDN telephone lines which consist of thirty channels each, allowing thirty simultaneous calls. PRI’s are the flagship of telephone line services, and deliver superior quality. These lines are monitored 24 hours a day allowing faults that occur on these lines to be identified and attended to at a much quicker turn around time.

200 DDI numbers are also available to you at no additional cost, with each PRI service. Again, when converting from other types of telephone lines to a PRI, your main telephone number will change. 

There are however, a number of ways we can assist you:

1.   By applying for a no charge, 3 months automatic diversion of all calls from your old telephone         number to your new one.

2.   By activating a message on the old number, informing callers to dial the new one.

3.   By retaining a few of the old telephone lines, so that you can still receive calls coming in on the       old telephone number, allowing you all the time you need to make your clients aware of the       new  telephone number.

VoIP telephone lines

Voice Over IP lines/channels allow one to make FREE calls over the internet. 

There are various products that once can make use of to achieve this through your PABX, which range from gateways to the international VOIP standard, SIP (Session Initiation Protocol).

Calls can be made over your ADSL line or dedicated diginet lines.

There are two most important aspects to consider when deciding to make use of VOIP:

1. The quality of the speech which one is going to get

2. The initial cost outlay required to set up VOIP

These are not simple ‘off the shelf’ solutions as they are made out to be, and making the wrong choice can be a devastating and costly exercise. If you are interested in these services, we suggest that you rather contact us to discuss in more detail.