Which channel for what: matching sixteen channels to your need, place and audience

There is no best channel, only a best channel for a given message, place and person. A login code, a delivery alert, a spring sale, a broken boiler and a mortgage interview each want something different. This guide puts the sixteen channels in our matrix side by side, as of October 2026, and then sorts them by need, by place and by audience. Each channel has its own primer, linked at the end, with the history, prices and rules in full.

The sixteen fall into four families, and the family explains most of the differences.

The chat apps are often called OTT ("over the top") services, because they run over the internet rather than through the operator's messaging service. Reach shrinks as you move down the list. The GSMA counts about 5.8 billion unique mobile subscribers, roughly 70% of the world's population;¹ the ITU estimates that 74% of people were online in 2025.² A chat app reaches only its own users in each country, and your app reaches only your customers. Richness grows in the other direction.

The most useful first question is not "which is cheapest?" but "who may send the first message?" Some channels let a business start, with the person's consent. Others only let the business answer.

• The business can start: SMS, RCS, voice and email, within consent rules; WhatsApp with a pre-approved template;³ Viber through an official partner; LINE, to people who added the account as a friend;⁶ push, once the person has allowed notifications.¹²¹³
• The customer starts: on Messenger and Instagram, a business may reply freely for 24 hours after the person writes; after that, a person (not a bot) may still answer for up to seven days with the human agent tag,⁴ and since 27 April 2026 Meta refuses three of the other message tags it once allowed;¹⁹ a Telegram bot cannot message anyone who has not opened it first;⁵ Apple Messages for Business conversations are always opened by the customer;¹¹ web chat starts with a visitor on your site.

Consent sits under all of it. In the United States, FCC rules require consent for automated or prerecorded marketing calls and texts to mobile phones.¹⁷ In the EU, consent under the GDPR must be freely given, specific, informed and unambiguous.¹⁸ See opt-in and consent is a data model.

Prices are built in a handful of ways, and the model matters more than the rate.

• Per message: SMS per segment, at a rate set by the destination country; WhatsApp per delivered template since 1 July 2025, by category and country, and since 1 October 2026 also for replies inside the customer service window: each business number gets 1,000 free service messages a month, after which they are charged, and utility templates sent inside an open window are now charged too;³ RCS per message, or per 24-hour conversation for agents set up for conversations, at prices set with mobile operators;¹⁰ Viber per message, by type and country.
• Per minute: voice per minute plus monthly number fees; video per participant-minute, with recording on top.
• Per volume tier: email, usually by monthly volume or per thousand.
• Per seat or subscription: Messenger, Instagram and Telegram usually carry no per-message platform fee, so the cost is the provider's inbox or bot; Apple provides Messages for Business free and the approved provider charges;¹¹ web chat is usually per agent seat.
• Per user: push and in-app chat, usually per monthly active user or device.
• Per plan: LINE official account plans include an allowance of messages sent by the business; WeChat usually charges an account verification fee rather than per message.

• Codes (OTP). Speed and reach matter most. SMS reaches almost any phone; a WhatsApp authentication template suits markets where WhatsApp is universal; voice reads the code to people whose texts fail. Email is too slow for most logins. See secure logins.
• Alerts. Deliveries, appointments, fraud warnings. Push is near-free for app users but best effort; SMS reaches everyone; RCS and WhatsApp add a brand and buttons. See notifications.
• Marketing. Only with consent, and the bar is rising: Google's sender guidelines require bulk senders to authenticate their mail and offer one-click unsubscribe.⁷ Email suits newsletters; WhatsApp, RCS and Viber suit short offers to opted-in customers; Messenger, Instagram, Telegram and Apple Messages are poor broadcast channels by design. See marketing campaigns.
• Support. Answer where the customer chose to write, and keep one history in a unified inbox. Video when the agent must see; voice when it is urgent or emotional. See customer support.
• Sales. Web chat at the moment of decision, WhatsApp or LINE for follow-up where they are everyday apps, video and email for business deals. Regulated onboarding may need a video identity check; India's central bank, for example, allows a video-based customer identification process.¹⁶ See sales.
• Commerce. Chat apps with payments and catalogues, Apple Messages with Apple Pay, LINE and WeChat in their markets, and a booking page on your own site. See selling inside the conversation and appointment booking.

Where your customers live changes the answer more than any feature. Internet use ranges from 94% in high-income countries to 23% in low-income ones, and averaged 36% in Africa in 2025, so channels that need data reach far fewer people in some markets than in others.² iPhones have supported RCS since iOS 18 in September 2024,⁸ but only with a carrier that supports it; availability varies by region and carrier, and iPhone users can switch RCS business messages off.⁹

Chat apps differ most from place to place. The best evidence is a named survey or the platform owner's own report, each with a date:

• WhatsApp. In Pew Research Center surveys in 2023 of eight middle-income countries (Argentina, Brazil, India, Indonesia, Kenya, Mexico, Nigeria and South Africa), a median of 73% of adults used WhatsApp, from 50% in India to 90% in Brazil.²⁰ In the UK, Ofcom found that WhatsApp reached 90% of online adults in May 2025.²¹
• Viber. Rakuten, which owns it, describes Viber as Ukraine's most widely adopted messaging app, installed on 98% of mobile phones there (January 2024),²² and as a leading messaging app in the Philippines (October 2024).²³
• LINE. LY Corporation reports about 100 million monthly users in Japan, 54 million in Thailand and 22 million in Taiwan, as of 31 March 2026.²⁴
• WeChat. Tencent runs Weixin for mainland China and WeChat as its international version, and puts their combined monthly users at over 1.4 billion at the end of March 2026.²⁵
• Telegram. We found no official figures for Telegram's users by country, so this guide does not rank its markets; see Telegram 101.

Treat these as starting points, not facts about your customers. Surveys cover some countries and not others, usage differs between neighbouring countries and between age groups in the same country, and a platform's own figures are not independently audited. Before committing, check a named, dated survey for each country, and your own data: which channels do customers already use to reach you? For sender registration country by country, see sender registration around the world. For one region in depth, see regional messaging in the Gulf.

• Age. Habits differ by generation. In the United States in April 2021, 27% of adults aged 18 to 49 made video calls at least daily, against 7% of those aged 65 and older.¹⁵ Older customers often prefer voice and SMS; younger ones may never read a text from an unknown sender but will answer in a chat app. Ask, and store the preference.
• Device. Apple Messages for Business reaches only Apple devices.¹¹ Push needs permission: Android 13 and later ask the user before an app may post notifications,¹² and iOS apps must ask before sending them.¹³ Video in the browser works on modern phones and computers with no download, because WebRTC is built into browsers.¹⁴
• Business or consumer. Business buyers live in email, calls and meeting links, and expect records they can forward. Consumers expect the chat app they use with friends, quick answers and few messages.

Each of these comes from the same mistake: choosing a channel for what it can do rather than for who it reaches and what they agreed to. The WhatsApp customer service window and the 24-hour window explain the most common case.

Few businesses need all sixteen. A practical mix is built in layers, and each layer keeps consent per channel, so a fallback never sends a message the person did not agree to. Seeing one customer across channels is what makes the mix omnichannel rather than many separate queues; see omnichannel is an identity problem.

Read the primer for each channel:

• Operator channels: SMS, RCS, voice.
• Open internet: email, video, web chat and booking pages.
• Chat apps: WhatsApp, Messenger, Instagram, Telegram, Viber, LINE, WeChat, Apple Messages for Business.
• Your own app: push notifications, in-app chat.

For choosing per message rather than per programme, read choosing a channel per message; for choosing the provider behind the channels, read how to choose a CPaaS provider.