Telephone Line Types

PSTN / Analogue lines, Multilines, BT Feature line, ISDN2 & ISDN30

Contact us now
to discuss
your telecoms
requirements
Contact Us

What are the different business telephone lines available?

PSTN / Analogue Telephone Lines

PSTN lines are normal analogue telephone lines. They do very little other than allow you to have a conversation. If you are a small business, you may be using PSTN lines. Call features include:

  • Caller Display
  • Call Minder Standard custom (1 Mailbox)
  • Call Minder Premium 5 custom (5 Mailboxes)
  • Call Barring
  • Call Diversion
  • Call Sign
  • Call Waiting
  • Reminder Call
  • Ring Back
  • Three-Way Calling

If you need to have more than one conversation at a time, you can add extra lines (auxilliary lines) and connect them to a small telephone system also known as switchboard or PBX/PABX.

PSTN Multilines

PSTN Multilines are lines that are on the same site and there is a link between the lines such that a single number is applied to all lines for incoming calls and the calls are routed to any line within the group.

BT Feature line

BT Feature line is a version of an analogue telephone line that provides basic PBX functionality and allows calls to be received and then transferred to another telephone line as well as some other features. The big disadvantage of feature lines is that you have to pay for a line for every separate phone extension. So, once you reach about 3 or 4 feature lines, it is probably time you considered another solution.

ISDN2 or ISDN2e

ISDN2 lines are ideal for businesses that require between 2 and 8 voice lines. If you need 8 lines or more, ISDN30 is a better option.

ISDN2e is does not require a survey. The appointment is booked and BT engineers (yes BT engineers will attend regardless of who you are buying the lines from) will turn up and, more often than not, get the ISDN2e installed successfully.

ISDN2e is installed in pairs of channels. Since this is a digital connection each line is referred to as a 'channel' and an ISDN2e line refers to a pair of channels (sometimes called a circuit).

Each ISDN2e line/circuit therefore provides 2 voice channels. If your business or organisation needs to have 4 simultaneous calls, you will need two ISDN2e lines/circuits providing four channels. If you need 6 simultaneous calls, you will need three ISDN2e lines/circuits providing 6 channels, etc.

ISDN2e call features include:

  • Calling Line Identity Presentation (CLIP)
  • Connected line Identity presentation (CLOP)
  • Sub Addressing (20 octet)
  • Incoming Calls Barred (ICB)
  • Permanent Outgoing Calls Barred (OCB)
  • Selective Outgoing Calls Barred
  • Customer Controlled Call Forwarding
  • Administration Call Forwarding
  • Call Deflection
  • Call Waiting with Call Hold
  • Presentation Number
  • Multiple Subscriber Numbering - Available for groups of size between 2 and 10 numbers

ISDN30

If your business needs at least 8 simultaneous voice connections to the outside world then, ISDN30 is a great solution.

You will have to pay for at least 8 lines so, if you need, say, 4 lines, you should consider installing ISDN2e. Note the functionality of ISDN30 and ISDN2e is identical. ISDN30 and ISDN2e only differ in their pricing (slightly) and the way in which they are delivered to your premises.

ISDN30 requires a site survey and can be pre-installed before the carrier brings the lines into service so it can be installed with a degree of control.

ISDN30 is delivered on copper wire or fibre optic cable. Note that there are some distance limitations with ISDN30 so premises in rural areas may struggle to get it installed. The carrier can always install it but if it means that it has to be delivered over fibre optic cable due to distance then this could cost extra. Where ISDN30 is not available you will be forced to install ISDN2e.

For most businesses, all you need is ISDN30 plus Caller ID and level 3 cover. You will also need an inbound number. Note all ISDN has limitations on the number of numbers. There are 5 number slots available. A slot can be taken by a single number or a range of numbers. A range of numbers has a minimum of 10 numbers in it in multiples of 10.

Most businesses may have one single number (one slot taken) and a range of Direct Dial numbers (10 for a small company, 100 for a larger company and so on). This example would leave 3 slots free for future use for a single number or range in each slot.

ISDN30 call features include:

  • Calling Line Identity Presentation (CLIP)
  • Connected line Identity presentation (CLOP)
  • Sub Addressing (20 octet)
  • Incoming Calls Barred (ICB)
  • Permanent Outgoing Calls Barred (OCB)
  • Selective Outgoing Calls Barred
  • Customer Controlled Call Forwarding
  • Administration Call Forwarding
  • Call Deflection
  • Call Waiting with Call Hold
  • Presentation Number
  • Multiple Subscriber Numbering - Available for groups of size between 2 and 10 numbers