Glossary

A business phone system is the set of phone numbers, internal extensions, users and call routing rules that a company uses to make and receive calls as an organisation rather than as individuals.

A cloud PBX (private branch exchange) is a business phone system that runs as an online service: the provider hosts the software that connects calls, and the business manages numbers, users and routing in a browser.

An extension is a short internal number, such as 101, that reaches a specific person, team or menu inside a company phone system without dialling a full phone number.

An IP phone is a physical telephone that connects to a phone system over a data network using VoIP, usually with the SIP protocol, instead of a traditional phone line.

A softphone is a software application that makes and receives phone calls over the internet on a computer, tablet or mobile phone, replacing a physical desk phone.

VoIP (voice over internet protocol) is technology that carries phone calls as data over the internet or another IP network instead of over traditional copper phone lines.

BYOC (bring your own carrier) is a setup in which a business connects a phone carrier of its choice to a cloud phone system, so calls use that carrier's network and numbers while the phone system provides routing, apps and call history.

Caller ID, also called CLI (calling line identification), is the phone number — and sometimes the name — shown to the person receiving a call.

A DID (direct inward dialing) number is a phone number provided by a carrier that delivers incoming calls to a phone system over the internet, where they can be routed to a person, team or call flow.

E.164 is the international standard, set by the ITU, for writing phone numbers: a plus sign, the country code and the national number without its leading zero, with no spaces and at most 15 digits.

Number porting is the process of moving an existing phone number from one carrier to another, so a business keeps the same number when it changes provider.

A SIP trunk is a virtual connection that carries phone calls between a phone system and a carrier over the internet using the SIP protocol, replacing physical phone lines.

A toll-free (freephone) number is a phone number that callers can dial at no cost, because the business that owns the number pays for incoming calls.

An AI voice agent is software that answers phone calls and holds a spoken conversation with the caller, following instructions written by the business — for example to answer common questions or take a message.

Business hours routing is a call routing rule that sends calls to different destinations depending on the time: to the team during opening hours, and to a message, voicemail or on-call number when the office is closed or on holidays.

A call flow is the sequence of steps an incoming call follows in a phone system — for example a greeting, a menu, a team and a voicemail — drawn or configured as a set of connected rules.

Call forwarding is a phone system feature that sends incoming calls to another destination — usually a mobile or external number — either always or only when certain conditions apply.

A call queue holds incoming callers in line, usually with music or messages, and connects each caller to the next available team member according to a distribution method.

Call routing is the set of rules that decides where an incoming phone call goes — for example to a person, a team, a menu, voicemail or a mobile number — based on conditions such as the number dialled, the time of day or the caller's choice.

A conference call is a phone call in which three or more people are connected at the same time, usually by dialling into a shared conference room, or bridge.

An IVR is an automated phone menu that plays a greeting and lets callers choose where their call goes, usually by pressing a number on their keypad.

Music on hold is the music or recorded messages a phone system plays to callers while they wait — on hold, in a queue or while a team is being rung.

A ring group is a set of users in a phone system who receive the same incoming calls, with the phones ringing either at the same time or one after another until someone answers.

Voicemail is a phone system feature that plays a greeting and records a message from the caller when a call is not answered, then makes the recording available to the person or team it was meant for.

AI call scoring evaluates recorded calls against a scorecard — a list of criteria such as a correct greeting or a clear next step — and gives each call a score with reasons and coaching suggestions.

Call metrics are measurements of how a phone line or team performs. Three common ones are average call duration (ACD), average wait time (AWT) and answer-seizure ratio (ASR), the share of calls that were answered.

Call recording is a phone system feature that saves the audio of phone calls as files, so they can be listened to, shared or analysed later.

Call transcription uses speech recognition to turn a recorded phone call into text. AI call insights build on the transcript with a summary, the sentiment of the call, the key topics and the share of time each side spoke.

A CRM phone integration, sometimes called CTI (computer telephony integration), connects a phone system to a CRM so that calls are logged on customer records automatically and users can call and look up customers from either tool.

A missed call, also called a lost call, is an incoming call that ended before anyone answered — the caller hung up while waiting or ringing, or reached no destination.

Call encryption protects VoIP calls from interception by encrypting both the signalling that sets up the call, usually with TLS, and the audio itself, usually with SRTP.

A codec (coder-decoder) is the method a VoIP system uses to turn voice into data for sending over a network and back into sound, balancing audio quality against bandwidth.

Fax over IP (FoIP) carries fax transmissions over an internet or IP network instead of an analogue phone line, most reliably using the T.38 protocol.