When installing a telephone system for the first time when you are setting up a new office, there are three main types of telephone line you can consider:
PSTN telephone lines… This is the most basic type of telephone line available. You will need a PSTN line to support any of the following devices or services:
- Fax machine connection
- Intruder or fire alarm systems
- Emergency lift telephones
- Analogue dial-up modems
- Remote access for maintenance support
- Franking machines.
With a PSTN line, it is only possible to have a single telephone number per line. This can be restrictive if you are planning to have multiple incoming call numbers for departments, or want individual direct dial numbers to increase the efficiency of your incoming call handling.
ISDN telephone lines… ISDN lines offer the very highest level of resilience and quality available for connection to the telephone network.
With ISDN lines, you can take advantage of supplementary features such as the ability to transfer incoming calls back out from your site to any external telephone number along with the ability to have additional numbering options for incoming calls known as DDI (direct dialling inwards) ranges.
There are two types of ISDN line available:
ISDN2… These are generally connected to phone systems with less than 8 external lines. ISDN2 lines are delivered in pairs so you can only operate with an even number of individual line rentals. They are powered from the local exchange with no power connection “on-premises” required to operate them.
ISDN30… This option is available if you have a requirement for 8 telephone lines or more. ISDN30 lines are presented on a single connection which can be upgraded to provide up to 30 telephone lines without the need for any additional cabling or engineering site visits. ISDN30 lines require power to be provided locally “on-premises”.
VOIP… A VOIP service connection allows you to make and receive telephone calls via the Internet as opposed to the telephone network. It offers a very high degree of flexibility with regards to numbering options. You can choose to have any UK STD code as your incoming number irrespective of your geographic location. This can prove very useful for some businesses when relocating “out of area” as you can take your fixed-line telephone with you anywhere.
The voice quality of speech via SIP trunks is very slightly lower than with ISDN lines and is a similar quality to a UK mobile telephone call. The quality of service level is also slightly lower because the response options to faults are traditionally slower with Internet providers than with telephone line providers. That said, the cost savings involved with VoIP telephone lines; no line rental, cheaper calls including International calls, and free calls between your organisation’s offices, make VoIP appealing to most businesses.
It is also worth keeping in mind BT’s intention to switch off the PSTN and ISDN networks by 2025. Businesses will need to migrate to a single IP core network that ultimately will replace all legacy networks and platforms. Thinking about migrating sooner rather than later could be very beneficial to your business, and it’s a good time to move onto new technology whilst setting up a new office.