Business communications
glossary.

10DLC (10-digit long code) is the US standard for business SMS from 10-digit numbers. Requires brand and campaign registration to avoid carrier filtering.

A2P (application-to-person) messaging is automated SMS sent from a software platform to a person — alerts, OTPs, reminders. Learn how it differs from P2P SMS.

Abandon rate is the percentage of inbound calls that disconnect before reaching an agent. It is a core contact center KPI tied to wait time and staffing.

ACW (After-Call Work) is the time an agent spends on post-call tasks like notes, CRM updates, follow-ups. AI reduces ACW by automating wrap-up work.

Agent occupancy is the percentage of an agent's logged-in time spent actively handling contacts. A core contact center KPI alongside utilization and shrinkage.

An ATA (Analog Telephone Adapter) is a small device that connects an old analog phone or fax to a VoIP service, bridging analog hardware to SIP signaling.

An auto attendant is an automated phone menu that greets callers and routes them to the right extension or department without a human receptionist.

ACD (Automated Call Distribution) is a system that routes inbound calls to the most appropriate agent or queue based on skills, availability, and rules.

AHT (Average Handle Time) is the total average time an agent spends on a customer interaction including talk, hold, and after-call work. Lower AHT means efficiency.

Average Speed of Answer (ASA) is the average number of seconds an inbound call waits in queue before an agent answers it. A primary call center service-level KPI.

Busy Lamp Field (BLF) is a phone key that shows whether a colleague's line is free, ringing, or on a call — and dials or picks up with one press. How it works.

BYOC (Bring Your Own Carrier) lets you keep your existing voice carrier while running a cloud UCaaS or CCaaS platform on top of their trunks. Here's how.

Call barging is when a supervisor joins a live call with both the agent and customer able to hear them. Used for urgent escalations and high-risk moments.

A call center is a voice-only customer service operation handling inbound and outbound calls. Contrast with omnichannel contact centers that add digital channels.

Call deflection offers waiting callers a digital alternative — SMS, chat, or callback — instead of holding, cutting queue load and abandonment. How it works.

Call flip moves an active call between your devices mid-conversation — desk phone to mobile to laptop — without hanging up or interrupting the other person.

Call forwarding redirects incoming calls to another number, device, or voicemail. Learn unconditional, busy, no-answer, and selective forwarding types.

Call park puts a live call on system-wide hold so any teammate can retrieve it from any phone by dialing a park slot. How it differs from hold and transfer.

A call queue is a virtual line that holds inbound callers in order and routes each to the next available agent when all lines are busy — the backbone of ACD.

Call routing software automatically directs inbound calls to the right agent or team using skills, time, and intent rules. Types, features, and setup explained.

Call screening identifies who is calling and why before you answer — from caller ID to AI screening that asks the caller's purpose. Methods compared.

Call whisper lets a supervisor speak to an agent during a live call without the customer hearing. Used for real-time coaching, especially in training scenarios.

Caller ID spoofing is faking the caller-ID number shown to the receiver — used for fraud and increasingly blocked by STIR/SHAKEN attestation.

CCaaS (Contact Center as a Service) is cloud-delivered contact center software for managing voice and digital customer interactions with AI, routing, and analytics.

CES (Customer Effort Score) is a CX metric measuring how easy it is for customers to resolve an issue or complete a task — a strong predictor of loyalty.

CNAM (Caller ID Name) is the caller-name delivery service that displays a registered name with an incoming call via a terminating-carrier database dip.

A conference call connects three or more participants in one audio session via a conference bridge — the basis of business audio conferencing on VoIP networks.

Conversational AI uses NLP and large language models to hold natural voice or chat conversations with customers — used in IVRs, AI receptionists, and bots.

CPaaS (Communications Platform as a Service) is a cloud platform that adds voice, SMS, and video to apps through APIs. Learn how it differs from UCaaS and CCaaS.

CSAT (Customer Satisfaction Score) measures how satisfied customers are with an interaction or overall experience. Post-interaction surveys, scale 1-5 typical.

A dial plan is the set of rules a phone system uses to interpret dialed digits and route each call — extensions, outside-line prefixes, and number formats.

A DID (Direct Inward Dialing) number is a virtual phone number that routes directly to a specific user or extension, eliminating the need for an operator.

Direct Routing connects Microsoft Teams to the phone network through your own SBC and carrier, giving Teams PSTN calling. How it works vs Operator Connect.

The Do Not Call (DNC) list is the US National Do Not Call Registry of phone numbers that have opted out of telemarketing calls. Scrub outbound lists or face fines.

DTMF (Dual-Tone Multi-Frequency) is the touch-tone signaling that pairs two sine waves per key, letting callers navigate IVR menus and dial on VoIP networks.

E.164 is the international phone number standard from the ITU that formats every number as +country code plus subscriber number, up to 15 digits total.

E911 (Enhanced 911) is the US requirement that phone service route emergency calls to dispatch with the caller's location. Critical for VoIP deployment compliance.

An Erlang is the unit of telecom traffic equal to one full hour of call activity. Call centers use Erlang B and Erlang C formulas to size staffing.

Find me/follow me rings your numbers and devices in sequence until you answer, so one business number reaches you anywhere. How it works and how to set it up.

FCR (First Call Resolution) is the percentage of customer issues resolved on the first interaction without a callback. Highest-leverage contact center metric.

G.711 is the ITU-T narrowband PCM codec that delivers toll-quality 64 kbps voice using A-law or mu-law — the baseline audio codec on PSTN and VoIP networks.

G.722 is an ITU-T wideband audio codec that doubles the frequency range of standard G.711 telephony — the basis of HD Voice on VoIP and SIP networks today.

HD Voice (wideband audio) doubles the frequency range of a normal phone call for clearer, more natural sound. How it works, codecs, and what it needs to work.

Hosted PBX is a cloud-based business phone system where the provider operates all infrastructure. No on-premises hardware, per-user subscription pricing.

A hunt group routes calls from one number across a group of extensions, ringing them in sequence or together until someone answers — a core PBX and VoIP feature.

ISDN (Integrated Services Digital Network) is a legacy digital telephony standard that carries voice and data over copper. Now being retired worldwide for SIP.

IVR (Interactive Voice Response) is an automated phone menu that routes callers using voice prompts and keypad input. Modern AI IVR understands natural language.

A jitter buffer holds incoming VoIP packets briefly to smooth out uneven arrival times, so audio plays back evenly. How it works and the latency trade-off.

Local presence dialing shows a local-area-code caller ID on outbound calls to lift answer rates. Learn how it works, the benefits, and the compliance rules.

MOS (Mean Opinion Score) rates VoIP call quality on a 1-to-5 scale. Learn what a good MOS score is and how jitter, latency, and packet loss lower it.

Music on hold plays audio to callers while they wait on hold or in queue. How it works, music licensing rules businesses miss, and message-on-hold tips.

NPS (Net Promoter Score) measures customer loyalty by asking how likely they are to recommend you. Industry standard for relationship-level customer sentiment.

Number porting is transferring your phone number from one carrier to another. Free on DialPhone, typical 2-5 business days, zero service interruption.

Omnichannel customer service unifies every customer touchpoint: voice, SMS, email, chat, social: into one continuous conversation with shared context.

Operator Connect adds PSTN calling to Microsoft Teams: pick a participating carrier in the admin center and they run the SBC. How it works vs Direct Routing.

Packet loss is data packets failing to reach their destination. On VoIP calls it causes choppy, robotic audio. Causes, acceptable thresholds, and fixes.

A PBX (Private Branch Exchange) is a business phone system that routes calls between internal extensions and the outside world. Traditional vs. modern cloud PBX.

A phone extension is a short internal number (like x101) that reaches a specific person or department behind one main business number. How extensions work.

POTS (plain old telephone service) is the analog copper-line phone network. What POTS lines are, why carriers are retiring copper, and replacement options.

A power dialer is an outbound dialing mode that automatically calls the next number on a list when an agent finishes the previous call — no manual click.

A predictive dialer auto-dials numbers ahead of agent availability to maximize talk time. Covers how it works, TCPA limits, and progressive vs preview dialing.

A preview dialer is an outbound dialing mode that shows the agent each contact and lets the agent decide when to place the call — no automatic dial.

A PRI (Primary Rate Interface) is a legacy ISDN trunk delivering 23 voice channels and 1 signaling channel over a T1 — now largely replaced by SIP trunking.

A progressive dialer is an outbound dialing mode that previews the next contact for a few seconds, then auto-dials when the agent confirms readiness.

The PSTN (Public Switched Telephone Network) is the traditional circuit-switched phone system. Learn how it differs from VoIP and why it is being retired.

QoS (Quality of Service) in VoIP prioritises voice packets on a network so calls stay clear under load. Jitter, latency, and packet loss are the metrics.

RCS (Rich Communication Services) is the GSMA messaging standard that upgrades SMS with branded sender identity, rich media, read receipts, and interactive cards.

A ring group rings several phones from one number — all at once or in sequence — so a call reaches the first available person. Ring strategies and setup.

A robocall is an automated phone call placed by software, often using a prerecorded message. Many are legal; many are scams targeted by TCPA and STIR/SHAKEN.

RTP (Real-time Transport Protocol) is the IETF standard for delivering live audio and video streams over IP. SIP sets up the call; RTP carries the voice.

Schedule adherence is the percentage of scheduled time an agent was actually in the planned state — on calls, on lunch, in training — when they were meant to be.

Call center service level is the percentage of contacts answered within a target time, like 80% in 20 seconds. Learn how it is calculated and why it matters.

A Session Border Controller (SBC) is a device that secures and controls VoIP traffic at the edge of a network. Learn what an SBC does and why SIP networks need one.

Shrinkage is the percentage of scheduled call center time agents are unavailable to take contacts — breaks, training, meetings, sickness, and absenteeism.

SIP (Session Initiation Protocol) is the signaling standard that sets up, manages, and ends VoIP calls. Learn how it works and how it relates to SIP trunking.

SIP ALG (Application Layer Gateway) is a router feature that rewrites SIP packets crossing NAT — often the hidden cause of dropped calls and one-way audio on VoIP.

A SIP phone makes calls over the internet using the SIP protocol instead of a phone line. Desk hardware vs softphone apps, setup, and how to choose.

SIP trunking delivers voice calls over the internet using Session Initiation Protocol. It connects on-premises PBX or SBC to a VoIP provider for PSTN access.

Skills-based routing matches each customer contact to the agent best qualified to handle it. Learn how it works, its benefits, and how it differs from basic routing.

An SMS short code is a 5- or 6-digit number leased via CTIA for high-throughput business texting — 100+ messages/second, top carrier trust, fast delivery.

A softphone is a software application that makes and receives phone calls using your computer, laptop, smartphone, or tablet instead of a physical desk phone.

Speech analytics mines call recordings for keywords, sentiment, and silence to surface compliance risks, coaching gaps, and customer-experience patterns.

SRTP (Secure Real-time Transport Protocol) is the encrypted variant of RTP that protects VoIP audio with AES encryption and HMAC integrity on the media path.

STIR/SHAKEN is the US framework for authenticating caller ID on VoIP calls to combat spam and spoofing. Required by FCC for carriers. Raises trust scores.

T.38 is an ITU-T standard for sending faxes in real time over IP networks, encoding fax data as packets that survive jitter and loss better than raw G.711.

The TCPA (Telephone Consumer Protection Act) is a US federal law restricting telemarketing calls, auto-dialed calls, and unsolicited SMS without prior consent.

Toll fraud is the criminal hijacking of a business phone system — usually a PBX or SIP trunk — to place expensive international calls billed to the victim.

A toll-free number is a phone number with an 800, 888, 877, 866, 855, 844, or 833 prefix where the business — not the caller — pays for the inbound call.

UCaaS (Unified Communications as a Service) is cloud-delivered business communications combining calling, messaging, meetings, and collaboration in one platform.

A vanity number is a phone number with a memorable pattern or a word spelled on the keypad, like 1-800-FLOWERS, used to lift brand recall and response.

A virtual callback lets a caller hang up while keeping their place in the queue, then receives an automated call back when an agent is available.

A virtual phone number is a cloud number not tied to one device or SIM. It routes calls and texts to any phone, app, or AI over the internet. How it works.

Visual voicemail shows your messages as a readable list you can play, read, and delete in any order — no dial-in required. How it works for business.

Voice broadcasting sends one pre-recorded phone message to many recipients at once. How it works, legitimate uses, and the TCPA rules that govern it.

Voicemail to text transcribes voice messages into readable text delivered by app, email, or SMS. How it works, accuracy factors, and business setup.

Non-fixed VoIP numbers are not tied to a physical address, unlike fixed VoIP. Learn the differences, use cases, and how non-fixed VoIP works for business.

VoLTE (Voice over LTE) is a packet-switched, IMS-based service that carries HD voice calls as IP data over a 4G LTE network instead of legacy 2G/3G circuits.

A warm transfer hands a call to a colleague after a brief introduction, passing context first. Learn how it differs from a cold transfer and when to use each.

WebRTC is an open standard that lets browsers make voice and video calls directly, with no plugins. Learn how it works and how it powers modern VoIP and meetings.

Workforce management (WFM) forecasts contact volume and schedules agents so the right number are staffed at the right times. Learn how call center WFM works.

A wrap-up code is a short label an agent applies at the end of a contact to record what it was about — refund, sales win, escalation — for reporting and coaching.