Glossary

10DLC stands for "ten-digit long code". In the United States, a business that texts customers from a normal local number must register its brand and every campaign (what the messages are for, with sample messages and how people opted in) through The Campaign Registry, usually via its messaging provider. Mobile operators filter or block unregistered traffic.

Why it matters when choosing a provider: ask who does the registration work, how long approval usually takes, what fees are passed through, and how your vetting result affects sending speed. Registration is specific to the US; other countries have their own sender rules.

When a customer messages a business on WhatsApp, a 24-hour window opens. Inside it the business can send any reply: text, images, buttons. Each new customer message restarts the clock. Once it closes, the business can only start a conversation with a pre-approved message template. Meta's Messenger and Instagram messaging have similar windows.

Why it matters: the window shapes support staffing, automation and cost. A reply that misses the window has to become a template, which needs approval in advance and is usually charged. Ask providers how their inbox shows the time left and what happens when it runs out.

A2P means "application to person": the sender is software, not a human typing on a phone. One-time codes, delivery updates, appointment reminders and promotional offers are all A2P.

Why it matters: mobile operators and regulators treat A2P traffic differently from personal messages. It usually has to travel over approved routes, use registered senders and follow consent rules, and it is priced differently. The details vary by country: brand and campaign registration in the US, DLT registration in India, sender name registration in Saudi Arabia, the UAE, Singapore and Australia. Sending business traffic as if it were personal traffic is a common reason messages are blocked.

Most businesses never connect directly to a mobile operator. Their messages pass through one or more aggregators, which hold the operator connections and route traffic onward. A CPaaS provider may be an aggregator itself, or buy routes from others.

Why it matters: every extra hop between you and the operator can add delay, cost and uncertainty about what happened to a message. Ask a provider which countries it reaches directly, which through partners, and how it reports delivery on indirect routes. "Grey routes", which carry business traffic over channels priced for personal messages, are a known source of blocked messages and compliance risk.

An AI agent goes beyond a scripted chatbot: it understands free-form questions, writes its own replies and can call other systems to get things done. Businesses use them for support, sales and bookings across chat, messaging apps and voice.

Why it matters: the useful questions are what the agent is allowed to do, how it hands over to a person, and how its answers are checked. In the EU, the AI Act requires that people be told when they are interacting with an AI system, with those transparency rules applying from August 2026; other jurisdictions are writing similar rules. A high "resolution" figure means little if customers simply gave up.

Instead of a number, the recipient sees a name like "MYBANK". It builds recognition and trust, but the recipient cannot reply to it, and it is not supported everywhere: the US and Canada, for example, do not allow it.

Because scammers imitate brand names, many countries now require alphanumeric senders to be registered before use. Examples include India (headers on the DLT platforms), Saudi Arabia and the UAE (sender name registration), Singapore (the national SMS Sender ID Registry) and Australia (the SMS Sender ID Register). The UK runs a voluntary industry registry. Ask providers which countries need registration, who files it and how long it takes.

An application programming interface is a set of requests a system accepts and the answers it gives back. In business communications, your website or CRM uses a provider's API to send a text, place a call or read a reply, without anyone touching a dashboard. Most modern communications APIs run over the web's own protocol, HTTP.

Why it matters when choosing a provider: good documentation, clear error messages, test accounts and stable versions save weeks of work. Ask how the provider announces changes and how long old versions keep working. Even if you never write code, your developers or integration partner will judge the provider here first.

Carriers, also called mobile network operators, own the last step to the phone. Text messages, calls and RCS all end on a carrier's network, so carriers set filtering rules, approve sender registrations in many countries and charge for business traffic.

Why it matters: when a message is blocked or delayed, the cause is often a carrier rule rather than the provider's software. Good providers explain each carrier's requirements, keep direct relationships where it counts, and pass carrier error codes back to you in plain terms. Messaging apps such as WhatsApp run over the internet instead, so carriers carry the data but do not control those messages.

CCaaS stands for "contact centre as a service". Instead of buying phone hardware and software for a support team, a business subscribes to a cloud product that routes calls and messages to the right agent, records conversations and reports on queues and service levels.

How it differs from CPaaS: CPaaS gives developers building blocks (send a message, place a call); CCaaS is a finished application for running a support or sales team. Many CCaaS products are built on CPaaS underneath, and some vendors sell both. Choose CCaaS when you need a working contact centre quickly; choose CPaaS when you want to build communications into your own product.

A chatbot replies to customers in a chat window, a messaging app or a text thread. Older chatbots follow decision trees and buttons; newer ones use language models to understand free-form questions and may act as AI agents.

Why it matters: a chatbot is only as good as what it can actually resolve and how cleanly it hands over to a person. Ask whether conversation history follows the customer to the human agent, whether customers can always reach a person, and how success is measured. Some channels, such as WhatsApp, have their own rules on automated messaging and disclosure.

A contact centre is the modern name for a call centre: the same idea, extended from phone calls to every channel customers use. It includes the people, the queues that decide who answers next, the scripts and knowledge they rely on, and the reports that show how long customers wait.

Why it matters: the technology choice (on-premises, CCaaS, or a CPaaS-built system) matters less than how work flows through it. Ask how a conversation that starts on one channel and continues on another keeps its history, and how quality is measured beyond speed.

Containment (sometimes called deflection) counts how many conversations a chatbot, AI agent or phone menu closed on its own. Vendors often quote it as proof that automation works.

Why to read it carefully: a conversation can be "contained" because the customer got an answer, or because they gave up, hung up or could not find a way to reach a person. A high containment rate with falling satisfaction or repeat contacts is a warning sign. Ask providers how they separate resolved conversations from abandoned ones, and whether they measure repeat contact within a few days.

CPaaS stands for "communications platform as a service". Rather than building connections to mobile operators, messaging apps and phone networks yourself, you call a provider's API and it delivers the SMS, WhatsApp message, call or video session for you, charging per use.

Why it matters when choosing: CPaaS providers range from global platforms to strong regional specialists. Compare them on the countries and channels you actually need, sender registration support, delivery reporting, data location, support quality and contract terms, not on headline channel counts. CPaaS is a set of building blocks; if you want a finished support desk, look at CCaaS instead.

Messages, call recordings and contact lists are personal data. Some laws restrict sending them abroad unless safeguards are in place (the EU's GDPR is a well-known example), and some sectors or governments require certain data to stay in the country, as banking and public-sector rules in several Gulf and Asian markets do.

Why it matters when choosing a provider: ask where message content, logs, recordings and backups are stored, which sub-processors can access them, and whether you can choose a region. Remember that a message still passes through the operator or messaging app on its way, so residency covers what the provider keeps, not the whole path.

After you send a text, the network can send back a delivery receipt: delivered, failed (with a reason code), expired or unknown. Messaging apps report similar states, often including "read". Providers pass these to you through a webhook or a report.

Why to read it carefully: "delivered" means the handset accepted the message, not that anyone read it or acted on it. Receipts are also only as good as the route: some networks and indirect routes return incomplete or even unreliable statuses. Ask providers how they source receipts in each country and how they translate error codes into something your team can act on.

Under the Telecom Regulatory Authority of India's regulations on unsolicited commercial communication (TCCCPR, 2018, since amended), businesses sending commercial texts in India register themselves, their sender headers and their message templates on platforms run by the mobile operators using distributed ledger technology. Messages that do not match a registered header and template can be blocked.

Why it matters: sending to India needs preparation before the first message. Ask providers whether they help with DLT registration, how template variables must be written, and how template mismatches show up in delivery reports. Other countries use different registration models, so do not assume one country's process applies elsewhere.

The General Data Protection Regulation has applied since May 2018 to organisations that handle personal data of people in the EU, wherever the organisation is based. It sets conditions for valid consent, gives people rights to access and delete their data, and limits transfers outside Europe.

It is one example among many. Others include the UK GDPR, Brazil's LGPD, South Africa's POPIA, India's Digital Personal Data Protection Act, and personal data protection laws in Saudi Arabia and the UAE. Marketing messages are often also covered by separate telecom or e-privacy rules. Ask providers which laws they support with features such as consent records, deletion and regional storage.

Interactive voice response is the "press 1 for billing" system on a phone line. Modern IVRs can understand speech, look up account details, take payments, or offer to continue the conversation by message instead of holding.

Why it matters: an IVR is often the first thing a customer experiences, and a long or confusing one drives people away. Ask providers how easily non-technical staff can change the menu, whether it supports the languages and dialects your callers speak, and how it passes what the caller already said to the agent who answers.

Journey orchestration connects events (a sign-up, an abandoned basket, an unpaid invoice) to actions (a welcome message, a reminder, a call from the team). Simple tools offer "if this, then that" rules; dedicated journey platforms add branching, waits, tests and channel choice across many steps.

Why it matters: the hard part is rarely the diagram; it is knowing who the customer is across channels, respecting their consent, and stopping a journey when they reply or buy. Ask providers where customer data and consent come from, how a journey reacts to a reply, and whether you can reach it through an API from the systems you already use.

Latency is delay. In a voice or video call it is the gap that makes people talk over each other; the ITU's planning guidance (G.114) treats 400 milliseconds one way as an upper limit and notes that conversation suffers well below it. In messaging it is the time between pressing send and the message arriving.

Why it matters when choosing: latency depends on distance, the number of hops and where media servers sit. For calls, ask where the provider's media servers are relative to your users. For one-time codes, ask for typical delivery times per country and route, measured on real traffic rather than quoted in a brochure.

A long code is a standard-length phone number in a country's numbering plan, as opposed to a short code. Businesses rent them as "virtual numbers" so customers can reply, call back or text in. They can be local, mobile or national numbers depending on the country.

Why it matters: whether a long code can send business texts at all varies widely. The US requires 10DLC registration; some countries allow business texts only from mobile-range numbers; others reserve business messaging for registered sender names or short codes. Ask providers which number types support two-way texting and voice in each country you need, and what documents are required to rent them.

Several channels require business-initiated messages to follow an approved template. On WhatsApp, templates are needed to start a conversation or to write outside the 24-hour window; Meta reviews each one and places it in a category (marketing, utility or authentication) that also sets its price. India's DLT system similarly requires SMS content templates to be registered.

Why it matters: templates are slow to change, so plan them like product copy. Ask providers how they help you draft, submit, translate and track templates, and how they report rejections, pauses or quality warnings.

Two-factor (2FA) or multi-factor (MFA) authentication combines something you know (a password), something you have (a phone or security key) and sometimes something you are (a fingerprint). Codes sent by SMS, voice or WhatsApp are a common second factor because almost everyone can receive them.

Why it matters: message-based codes are convenient but not the strongest option. The US National Institute of Standards and Technology classes codes sent over the phone network as a "restricted" authenticator because of risks such as SIM swap and interception. Many businesses offer stronger options alongside them and add checks like SIM swap detection for high-risk actions.

Number portability lets a person or business keep their number when they switch providers. Regulators in many regions require it, including the US (FCC), the UK (Ofcom) and the European Union under its telecoms code, and many countries in the Middle East, Africa and Asia have their own schemes. Rules on which number types can move, and how quickly, differ by country.

Why it matters when choosing a CPaaS provider: a published support number or SMS number is an asset. Before signing, ask whether you can port your existing numbers in, and just as important, whether you can port them out if you leave. Get the process and typical timelines in writing.

"Multichannel" means a business is reachable on many channels. "Omnichannel" means those channels share one view of the customer: if someone emails, then sends a WhatsApp message, then calls, the person who answers sees all of it.

Why it matters: omnichannel is mostly a data problem, not a channel count. It depends on recognising the same person across a phone number, an email address and a messaging account, and on keeping consent per channel. Ask providers how they match identities, what happens when matching fails, and whether history moves with the customer when a conversation changes channel.

A one-time password proves a person has access to a phone number or device right now. Codes can be delivered by SMS, voice call, WhatsApp or RCS, or generated in an authenticator app using an open standard (TOTP).

Why it matters when choosing a provider: for delivered codes, speed and reliability are the whole product. Ask for delivery times by country, automatic fallback to another channel when a code does not arrive, and protection against "SMS pumping", a fraud in which bots trigger codes to expensive numbers to generate revenue for the fraudster. Delivered codes are also exposed to SIM swap, so consider stronger methods for high-risk actions.

Opt-in means the person said yes before the business wrote to them: by ticking a box, texting a keyword, or agreeing at checkout. Laws and platforms set the conditions. The EU's GDPR requires consent to be freely given, specific, informed and unambiguous; US texting rules and industry guidelines expect clear consent for marketing; WhatsApp requires businesses to obtain opt-in that names the business before messaging people.

Why it matters: consent is a record, not a checkbox. Store who agreed, to what, on which channel, when, how, and what they were shown. Ask providers whether they can store and check consent before every send.

Opting out can be as simple as replying "STOP" to a text, tapping a button in a messaging app, or using a national do-not-disturb register. India's regulations let people block categories of commercial messages; US rules and industry guidance expect common keywords like STOP to work; data protection laws such as the GDPR let people withdraw consent as easily as they gave it.

Why it matters: an opt-out must reach every system that sends, on every channel the person withdrew from. Ask providers whether opt-out keywords are handled automatically in each country and language (including Arabic), and whether opt-outs sync back to your CRM.

"Over the top" means the service rides on top of a data connection. WhatsApp, Messenger, Telegram, Viber and similar apps are OTT. They offer rich features such as images, buttons and read receipts, but only reach people who have installed the app, and each app sets its own business rules and prices.

Why it matters: which OTT apps people actually use differs sharply by country, so a channel that dominates in one market may be marginal in the next. SMS still reaches almost every phone. Many businesses combine an OTT channel with SMS as a fallback. Some governments also restrict OTT calling, so check local conditions.

P2P stands for "person to person": a friend texting a friend. Mobile operators price and filter it differently from business (A2P) traffic, expecting low volumes, two-way conversation and no automation.

Why it matters: sending business messages through personal-style routes or SIM cards to save money (sometimes called "SIM farms" or grey routes) breaks operator rules in most countries and gets numbers blocked. A legitimate provider will be clear that your traffic is A2P and route it accordingly, even when a person is replying by hand from a shared inbox.

The public switched telephone network is what you reach when you dial a normal number. Its numbering follows an international plan (ITU-T E.164), which is why every number has a country code. Much of it now runs over internet technology behind the scenes, but the rules, numbers and operators remain.

Why it matters: an app-to-app call or WebRTC call stays on the internet and is cheaper and richer; a call to or from a real phone number has to "break out" to the PSTN, which brings per-minute charges, local licensing and number rules. Ask providers in which countries they can offer numbers and outbound calling, and under what conditions.

Rich Communication Services is specified by the GSMA as the "Universal Profile". For businesses, it means messages that arrive in the phone's default messaging app with the brand's verified name and logo, rich cards, suggested replies and delivery and read status. Since Apple added RCS support to iPhone in 2024, it works on both major phone platforms where operators enable it.

Why it matters: availability still depends on the country, the operator and the handset, and each brand must be verified before sending. Most programmes send RCS where possible and fall back to SMS automatically. Ask providers which countries and operators they reach and how fallback is reported.

A software development kit wraps a provider's API in code your developers can drop in. For messaging it saves writing requests by hand; for voice and video it often does much more, handling microphones, cameras, network changes and the user interface on phones and browsers.

Why it matters: an SDK ties part of your app to one provider. Ask which platforms are supported (iOS, Android, web), how often the SDK is updated, how large it is, and what happens to your app if you switch providers later. Open standards such as WebRTC reduce how much you depend on any single SDK.

Every business text shows a sender: a long number, a short code or an alphanumeric name. Which types are allowed, and whether they must be registered first, is decided country by country, by regulators and mobile operators.

A few examples of how it differs: the US uses registered 10DLC numbers, toll-free numbers and short codes rather than names; India requires headers to be registered on DLT platforms; Saudi Arabia and the UAE require sender name registration; Singapore and Australia run national sender ID registers. Why it matters: an unregistered sender can mean blocked messages, or messages labelled as suspicious. Ask providers to list requirements and lead times for each country you send to.

An SLA usually promises a percentage of availability per month, response times for support tickets by severity, and service credits if targets are missed.

How to read one: check what is actually covered (the API being reachable is not the same as messages being delivered, which also depends on operators and messaging apps), how downtime is measured, what is excluded, and whether credits are automatic or must be claimed. Credits are usually small compared with the business cost of an outage, so the provider's track record, visible on its status page history, often matters more than the number in the contract.

Short codes are easy to remember and text to ("Text JOIN to 12345"). They usually support high sending volumes and are approved by mobile operators in advance. Length, cost and rules are set nationally: in the US they are leased through a registry run by the wireless industry association, CTIA, and in other countries they may be assigned per operator or shared between several businesses.

Why it matters: short codes are typically the most expensive and slowest sender type to obtain, often taking weeks. They suit large, sustained programmes in one country. Ask providers about lead times, monthly fees and whether a code works across all operators in that country.

In SIM swap fraud, a criminal persuades an operator to move a victim's number to a new SIM, then receives their one-time codes. A SIM swap check lets a bank or app ask, before sending a code or approving a payment, whether the number's SIM changed in the last few hours or days.

Operators increasingly offer this through standard network APIs, notably the GSMA Open Gateway initiative built on the open-source CAMARA specifications. Why it matters: coverage varies by country and operator. Ask providers where checks are available, what they cost, and how results feed your risk decisions.

The Session Initiation Protocol, defined by the IETF, is the common language that internet phone systems use to place a call, ring the other side, transfer it and hang up. The audio and video themselves travel separately; SIP handles the arrangements.

Why it matters: if your business already has a phone system or contact centre, SIP is usually how it connects to a provider's network or to other platforms. Ask providers whether they support standard SIP connections, which codecs and security options (such as encrypted signalling and media) they offer, and which phone systems they have tested with.

A SIP trunk is a virtual bundle of phone lines delivered over an internet connection. It lets a company's phone system or contact centre make and receive ordinary phone calls, with numbers and capacity added or removed without new wiring.

Why it matters: SIP trunking is often how businesses keep their existing phone numbers and carrier while adopting a new cloud contact centre ("bring your own carrier"). Ask providers about the countries where they offer numbers and emergency calling, how many simultaneous calls are included, redundancy if a connection fails, and how call quality is monitored.

Short Message Peer-to-Peer (SMPP) dates from the 1990s and remains the common way providers and operators pass SMS traffic and delivery receipts to each other over a persistent connection. Most businesses today use a provider's web API instead, which the provider translates into SMPP further down the chain.

Why it matters: if you send very high volumes, run your own messaging software, or are switching from a provider that gave you an SMPP connection, ask whether the new provider supports SMPP, how many connections and messages per second it allows, and how delivery receipts are returned. For everyone else, a modern HTTP API is usually simpler.

Most communications providers publish a status page listing each service (messaging API, voice, a given country or channel) with its current state and an incident history. Many let you subscribe to alerts by email or webhook.

Why it matters when choosing: the history is free due diligence. Look at how often incidents happen, how quickly they are acknowledged, whether updates are specific, and whether post-incident reports explain causes. Compare what you see with the uptime promised in the SLA. A provider that reports problems openly is usually easier to work with than one whose page is always green.

Throughput is sending speed. It is limited at several levels: your provider's account settings, the sender type (short codes usually allow more than long codes), registration results such as US 10DLC vetting, and channel rules such as WhatsApp's messaging limits, which grow with a business's quality and history.

Why it matters: a flash sale or an emergency alert to a large list can take minutes or hours depending on throughput. Ask providers what limits apply to your account and senders in each country, how messages are queued when you exceed them, and how limits can be raised. Treat a single "messages per second" figure without context with care.

Toll-free numbers use special prefixes set by each country, such as 800 and similar codes in the US and Canada, 0800 in the UK and many European countries, and 800 numbers in several Gulf states. Note that mobile callers may still pay for airtime in some countries.

Why it matters: in many countries toll-free numbers are voice-only. In the US and Canada they can also send business texts after a verification process. Ask providers whether a toll-free number can be reached from mobiles and from abroad in each country you need, whether it supports texting, and what the per-minute cost to you is.

WebRTC tries to connect callers directly. When a corporate firewall, a hotel network or a mobile operator blocks that, the media goes through a TURN relay instead. TURN is an IETF standard (RFC 8656), usually paired with STUN, which helps devices discover how to reach each other.

Why it matters: without TURN, a share of calls simply fail to connect, often for exactly the business users you care about. TURN traffic also costs bandwidth. Ask video and voice providers whether TURN is included, where their relay servers are located relative to your users, and whether relayed traffic is charged separately.

UCaaS stands for "unified communications as a service". It replaces the office phone system with a cloud service that gives every employee a business number, video meetings and chat on any device.

How it fits with the others: UCaaS is mainly for employees talking to each other and to the occasional outside caller; CCaaS is for a team handling customer conversations at volume; CPaaS is building blocks for developers. The lines blur, as many vendors sell bundles, but knowing which problem you are solving keeps you from paying for features you will not use.

A unified inbox gathers conversations from many channels so agents do not switch between apps. Good ones show the customer's history across channels, assign conversations to the right person, show channel rules such as the WhatsApp 24-hour window, and hand over cleanly between bots and people.

Why it matters: this is where your team spends its day, so usability counts as much as features. Ask providers which channels are native and which go through add-ons, whether Arabic and right-to-left text display correctly, how conversations are routed and reported, and whether the inbox connects to your CRM.

An API is you asking the provider to do something; a webhook is the provider telling you something happened. You give the provider a web address, and it sends an event there for each inbound message, delivery receipt, call status or template approval.

Why it matters when choosing a provider: much of a messaging programme runs on webhooks, so their reliability matters. Ask whether webhooks are signed so you can confirm they are genuine, how failed deliveries are retried, whether events can arrive out of order or twice, and how long you can replay missed events. Open conventions such as Standard Webhooks describe good practice.

WebRTC, standardised by the W3C and the IETF, gives browsers and apps the ability to capture a microphone and camera, connect to another person and send encrypted audio, video and data in real time. It powers many "click to call" buttons, video consultations and in-app calls.

Why it matters: because WebRTC is an open standard, you are not locked into one vendor's technology for the basics. What providers add is the infrastructure around it: servers for group calls, TURN relays, recording, and links to the phone network. Ask where those servers are, how calls are recorded and stored, and what happens on poor networks.

The WhatsApp Business Platform (often called the WhatsApp Business API) is different from the free WhatsApp Business app used on a single phone. It connects to software, supports many agents and automation, and follows Meta's rules: businesses must collect opt-in, use approved templates to start conversations, respect the 24-hour customer service window, and pay according to Meta's pricing by message category and country.

Why it matters when choosing a provider: many providers resell access and add an inbox, automation and support on top. Ask what they add beyond Meta's own fees, who owns the business account and phone number, and whether you could move both if you leave.