Plain-English definitions for the terms behind modern phone systems and contact centres — UCaaS, CCaaS, IVR, ACD, predictive dialer, skills-based routing, CSAT, AHT, first-contact resolution, abandonment rate, AI agent, workforce management, and more.
The percentage of inbound calls that callers disconnect before reaching an agent.
In a contact center, abandonment rate measures how often callers hang up while waiting in a queue before an agent answers. A high abandonment rate typically signals insufficient agent capacity, poor queue management, or unrealistic wait times. Abandonment rate is a core contact center metric monitored alongside average handle time and service level.
→ Call QueuesAutomatic Call Distributor.
A system that receives inbound calls and routes them to the appropriate agent or queue based on configurable rules. ACD logic typically considers agent availability, skills, caller input, and queue priority. Modern ACD systems are usually part of a contact centre platform rather than a standalone device.
→ Call RoutingAverage Handle Time.
The average total time an agent spends on a call, including the conversation itself and any after-call work such as logging notes or updating a CRM record. AHT is a widely used contact centre metric but should be interpreted alongside quality metrics — very low AHT may indicate rushed interactions.
→ Contact CenterAn automated system that handles customer conversations — voice or chat — without a human agent.
An AI agent uses natural language understanding to identify what a customer wants and either resolves the request from a knowledge base, collects structured information, or escalates to a human agent when the interaction requires it. AI agents are deployed on voice channels (as AI voice agents or AI receptionists) and digital channels (as AI chat agents). When escalating, the AI passes the conversation context to the human agent so the customer does not need to repeat themselves.
→ AI AgentsAn automated system that answers inbound calls and routes callers using a menu.
An auto attendant greets callers, presents options (by voice prompt or keypad), and routes calls to the appropriate extension, team, or queue without requiring a human receptionist. Sometimes used interchangeably with IVR, though technically an IVR can interact with back-end systems to retrieve information, while a basic auto attendant only routes calls.
→ Auto Attendant FeatureA supervisor mode that joins a live call as a full participant, audible to both agent and caller.
Barge (or barge-in) allows a supervisor to join an active call so that all three parties — supervisor, agent, and caller — can hear and speak to each other. Typically used to resolve escalations or take over calls where an agent is unable to assist. Distinguished from Whisper (agent-only coaching) and Listen (silent monitoring).
→ Call MonitoringA holding system that places inbound callers in line until an agent becomes available.
When all agents are busy, inbound calls are placed in a queue. The caller hears hold music or messages while waiting. Queue management systems can announce estimated wait times, offer callbacks, or route callers to voicemail or alternative channels. Queue configuration — ring strategy, maximum queue size, timeout behaviour — significantly affects caller experience.
→ Call Queues FeatureContact Center as a Service.
A cloud-delivered contact centre platform providing inbound and outbound call handling, queue management, routing, recording, analytics, and often AI-assisted tools. CCaaS replaces on-premise contact centre hardware and software with a subscription-based cloud service. Related to UCaaS, which is the broader unified communications equivalent. See also: Contact Center vs Call Center.
→ What Is CCaaS?Compare CCaaS platforms: MCC vs Five9, MCC vs Genesys, MCC vs Talkdesk.
Customer Satisfaction Score.
A measure of how satisfied a customer was with a specific interaction, typically gathered via a post-call or post-chat survey asking the customer to rate their experience. CSAT is often expressed as a percentage of respondents who gave a positive rating. It is one of several customer experience metrics used alongside NPS (Net Promoter Score) and FCR (First-Call Resolution).
→ Contact CenterDirect Inward Dialing.
A phone number that routes directly to a specific extension, user, or department within a business phone system, without passing through a receptionist or main number. DIDs allow businesses to give individual team members or departments their own callable number. Virtual phone numbers are DIDs delivered via VoIP rather than a physical line.
First-Call Resolution (also First-Contact Resolution).
The rate at which customer issues are resolved on the first contact, without the customer needing to call back or be transferred to another agent. FCR is considered one of the strongest indicators of contact centre effectiveness. Improving FCR typically requires the right routing (connecting callers to the most capable agent), good agent training, and access to relevant customer information. Sometimes called First-Contact Resolution to account for non-voice channels.
→ Skills-Based RoutingInteractive Voice Response.
A system that allows callers to interact with a phone system via voice input or keypad. Unlike a basic auto attendant (which only routes calls), a full IVR can retrieve information from back-end systems — for example, reading back an account balance or order status — and handle certain queries without a human agent. Modern IVRs increasingly use natural language processing rather than DTMF keypad navigation.
→ IVR FeatureManaging customer communications across multiple channels — voice, chat, WhatsApp, email, SMS — from a unified platform with shared customer history.
An omnichannel approach ensures that a customer's conversation history is visible regardless of which channel they use. An agent handling a follow-up call can see the WhatsApp thread that preceded it. This differs from a multi-channel approach, where channels are managed separately and agents lack a unified view. MCC's Omnichannel platform supports: Website Chat, WhatsApp, Instagram, Facebook Messenger, Telegram, SMS, and Email — all in a single agent inbox.
→ OmnichannelAn outbound dialing system that calls multiple numbers simultaneously and connects answered calls to available agents.
A predictive dialer dials more numbers than there are available agents, using an algorithm to predict agent availability and answer rates. When a call is answered, the system connects it to the next available agent. This maximises agent talk time by minimising idle time between calls. Predictive dialers are most effective for large outbound teams and high-volume campaigns. They are subject to abandonment rate regulations in many jurisdictions — calls connected to no available agent are "abandoned." Compare with progressive dialer (1:1 ratio) and preview dialer (agent chooses when to dial).
→ Sales DialerPrivate Branch Exchange.
The telephone switching system used within a business to route internal calls between extensions and to connect internal extensions to external phone lines. Traditional PBX systems were physical hardware installed on-premise. Cloud PBX (hosted PBX) delivers the same functionality via software over the internet, without requiring on-site hardware.
→ Business PhoneSession Initiation Protocol.
The signalling protocol used to establish, modify, and terminate VoIP calls and other multimedia communication sessions. SIP is an IETF standard (RFC 3261) and is widely used across business telephony. SIP trunking uses SIP to replace traditional physical phone lines (such as ISDN or PRI circuits) with internet-based voice channels.
→ What Is SIP Trunking?A virtual phone connection delivered via SIP over the internet.
A SIP trunk connects a business phone system to the public telephone network via an Internet Telephony Service Provider (ITSP). Unlike ISDN or PRI circuits, SIP trunks do not require physical lines — capacity is provisioned in software. SIP trunks can carry multiple concurrent calls over a single broadband connection and are used by both cloud phone systems and on-premise PBX systems.
→ Wholesale VoiceRouting inbound calls to the agent best equipped to handle the specific query.
Rather than routing calls to any available agent, skills-based routing uses information about the caller (such as the number they dialled, their language preference, or their history) and agent attributes (such as language, product knowledge, or previous interactions) to connect them to the most appropriate agent. This can improve first-call resolution and reduce transfers.
→ Skills-Based Routing FeatureService Level Agreement.
In contact centre usage, SLA most commonly refers to the target percentage of inbound calls answered within a specified number of seconds — for example, "answer 80% of calls within 20 seconds." SLA performance is a core contact centre metric. The term is also used in provider contracts to describe the availability or uptime commitments a cloud vendor makes to customers.
→ Contact CenterA software application that makes and receives calls over VoIP from a computer, tablet, or mobile device.
A softphone replaces a physical desk phone with a software interface — typically a desktop app or browser-based client. Calls use VoIP (voice over IP) rather than the PSTN. Softphones allow employees to make and receive business calls from any device with an internet connection, which is particularly useful for remote or hybrid teams.
→ Business PhoneAutomatically converting call audio into text.
AI-powered call transcription converts the spoken audio of a call into a text record in near real time or after the call. Transcripts can be used for quality assurance, agent coaching, call search and retrieval, and feeding into analytics or CRM records. Transcription accuracy varies by provider, audio quality, and language/accent. Related to sentiment analysis, which analyses the tone and content of transcripts.
→ AI Transcription FeatureUnified Communications as a Service.
A cloud-delivered platform that combines voice calling, messaging, and often video conferencing into a single service. UCaaS replaces on-premise PBX hardware with a cloud subscription model. The "unified" aspect refers to the consolidation of multiple communication channels — calls, SMS, team messaging — accessible from one application. CCaaS (contact centre) is a related but distinct category focused on inbound/outbound customer interactions at scale.
→ What Is UCaaS?Compare UCaaS platforms: MCC vs RingCentral, MCC vs Dialpad, MCC vs 8x8, MCC vs Zoom Phone, MCC vs Nextiva.
Planning and scheduling tools that match agent capacity to expected contact volume.
Workforce management (WFM) in a contact centre context covers the planning, scheduling, and monitoring of agent capacity. This includes forecasting call and contact volumes, scheduling the right number of agents for each time period, tracking adherence (whether agents are working as scheduled), and real-time adjustment when volumes deviate from forecast. WFM reduces both overstaffing (wasted cost) and understaffing (long wait times and poor service levels).
→ Contact CenterVoice over Internet Protocol.
A technology that carries voice calls as digital data packets over an IP network (such as the internet or a private LAN) rather than the traditional PSTN. VoIP is the underlying technology behind SIP trunking, cloud PBX systems, softphones, and UCaaS platforms. Call quality over VoIP depends on network bandwidth, latency, and jitter — all manageable with QoS (Quality of Service) settings on business networks.
→ Business PhoneA supervisor mode that lets a supervisor coach an agent during a live call, inaudible to the caller.
Whisper coaching allows a supervisor to speak to an agent during an active call without the caller hearing the supervisor. This is used to guide agents in real time — suggesting responses, alerting them to policy considerations, or helping with difficult calls — without interrupting the conversation from the caller's perspective. Compare with Barge (all parties hear the supervisor) and Listen (silent monitoring only).
→ Call MonitoringSee how these building blocks come together in one cloud platform.