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Telecoms Jargon Explained In Plain English

If you’ve been researching business telecoms solutions, you’ve probably been hearing a lot of unfamiliar terms. Things like FTTC connections, leased lines, PBXs, and many other bits of jargon. We’ve put together an index of telecoms jargon, explained in plain English, to help you make sense of all the options available.

On-Premises Telecoms

On-premises telecoms refers to any telecoms technology where the majority of the telecoms hardware is physically located on your premises. On-premises phone systems often use a dedicated PBX (see below). 

Cloud-Based Telecoms

Like cloud computing, cloud telecoms refers to a telecoms technology where all the infrastructure and hardware is housed off-site at a provider’s data centre. Most VoIP platforms are cloud-based (see below for more information about VoIP).


PBX stands for Private Branch Exchange. It refers to a private phone network used and managed by a business or organisation. They switch route calls to internal lines and allow users to access a shared pool of external phone lines.

A PBX can be a piece of physical hardware, but today, off-premises, cloud-based PBX systems are far more common.


VoIP stands for Voice over Internet Protocol. This is a technology which converts analogue voice signals into digital “packets” which can be sent over the internet. If you have used Skype or made a voice call over WhatsApp, then you have already used VoIP. The call quality of VoIP is usually better than an analogue phone line and the call costs can be significantly less.

On-premises VoIP solutions are available, but most businesses prefer the convenience of cloud-hosted VoIP.

FTTC Broadband

FTTC stands for Fibre To The Cabinet. It is a type of broadband which uses high-speed fiberoptic cable to transmit data from the internet service provider (ISP) to the nearest telephone exchange cabinet. The connection from the cabinet to your premises (sometimes known as the “last mile”) is still made using standard copper telephone lines.

FTTP Broadband

FTTP stands for Fibre To The Premises. FTTP is a type of broadband which uses high-speed fiberoptic cable to transmit data from the internet service provider. However, unlike FTTC, fibreoptic cable is used for the entire connection, all the way to your business premises. Because FTTP uses fibreoptic cable for the entire connection, the speed of an FTTP connection is significantly higher than an FTTC connection.   

Leased Lines

A leased line is a fibre broadband line that, unlike a FTTC or FTTP line, does not connect to your property via a cabinet or exchange, instead it runs directly from your internet provider to your premises. 

A leased line is dedicated to your company alone and is not shared with anybody else. Ordinary business broadband lines are frequently shared by as many as 20 other users. 

Leased lines offer the fastest and most reliable business broadband connections available on the market.  

PSTN (Public Switched Telephone Network)

The public switched telephone network is the “traditional” analogue phone network that has been in operation for the last century. It uses copper cables to send analogue voice signals across long distances. Currently, it is being phased out and new PSTN circuits will become unavailable by the end of 2025. Businesses which still rely on PSTN phone lines need to start thinking about switching to an alternative soon.   

ISDN (Integrated Services Digital Network)

ISDN is a digital network which runs over existing copper telephone wire. Unlike the older PSTN network, ISDN allows you to transfer data, voice, video, and fax messages over a single line. 

Like the PSTN network, ISDN lines are also being gradually phased out. From the end of 2025, new ISDN lines will not be available. Businesses which rely on ISDN need to look at fibreoptic cable alternatives. 

Telecoms Disaster Recovery

Telecoms disaster recovery refers to plans, technologies, and procedures which allow your business to maintain communications after a disaster. This can include fallback systems such as hosted VoIP which allows your team to stay in contact even if they are unable to enter your premises.  

Many businesses will choose to partner with a third-party provider for their disaster recovery planning and support. A disaster in this context could be something physical like an office fire, or something digital like a ransomware attack. 

MPLS (Multiprotocol Label Switching)

Multiprotocol Label Switching (MPLS) is a protocol for labelling and routing different “packets” of data across a network. The benefit of implementing MPLS is that your network will become more efficient. This is because the packets can be sent to the destination on their label without needing to inspect it first. It also allows you to prioritise the transmission of critical data.

SIP Trunk

An SIP trunk is the virtual equivalent of a land line. By connecting your VoIP platform to an SIP trunk, you can make and receive landline calls using VoIP.  

Hopefully, this has been a useful explainer, not just about telecoms jargon, but also the many services which we offer at Carden Telecoms. If you’d like to learn more about any of the telecoms technology discussed here and how it could benefit your business, speak to our team today. 

Author: Dave King

Dave King is the Co-Founder and Director of Carden Telecoms and the wider Carden IT Group. Dave is experienced in business telecoms with a focus on cloud telephony and connectivity services.

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