Guide
Telecoms Glossary
Telecoms terminology explained simply, without the jargon.
In this guide
Common terms explained
- VOIP (Voice over Internet Protocol)
- Making and receiving phone calls over the internet instead of a traditional phone line.
- PSTN (Public Switched Telephone Network)
- The UK's traditional analogue copper phone network, currently being retired nationwide.
- SIP (Session Initiation Protocol)
- The technical standard most VOIP and virtual landline systems use to set up and manage calls.
- PBX (Private Branch Exchange)
- A phone system that manages calls within a business — routing, extensions, queues and voicemail. A "Cloud PBX" does this over the internet rather than on physical office hardware.
- Virtual Landline
- A business or home phone number that works over the internet rather than a physical line — see our full guide.
- Landline SIM
- A SIM card that gives a mobile device a landline-style number, without needing a physical line.
- FTTC / FTTP
- Fibre to the Cabinet / Fibre to the Premises — describes how far fibre-optic cable runs before switching to copper (FTTC) or going all the way to your building (FTTP).
- Leased Line
- A dedicated, uncontended internet connection reserved solely for one business — reliable but more expensive than shared broadband.
- Contention Ratio
- The number of users sharing the same broadband connection — a 1:1 ratio (as with a leased line) means it's not shared at all.
- Static IP Address
- A fixed internet address for your connection, rather than one that changes each time you reconnect — often required for VOIP systems or remote access.
- Failover / Backup Connection
- A secondary internet connection that automatically takes over if the primary connection drops.
- Cat5e / Cat6 / Cat7
- Categories of network cabling, each supporting higher speeds and better shielding than the last — Cat7 is the most capable of the three.
- SSID
- The name of a WiFi network, as seen when a device searches for available networks.
Frequently Asked Questions
What's the difference between VOIP and a virtual landline?
VOIP is the underlying technology (calls over the internet); a virtual landline is a specific type of VOIP service designed to replicate a traditional business or home landline number.
Do I need to understand all of these terms to switch to VOIP?
No — we handle the technical setup. This glossary is here if you want to understand what's being discussed.
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