WhatsApp, SMS, email or a call? Choosing the channel UK customers answer

Most comparisons of business messaging channels are written by a company that sells one of them. So WhatsApp vendors find WhatsApp wins, SMS vendors find SMS wins, and nobody includes the phone call. This guide covers all four main channels for a UK business, using regulator data where it exists and saying so where the evidence is thin.

The four channels at a glance

WhatsApp: where your customers already are

Ofcom's Online Nation report measured WhatsApp reaching 90% of UK online adults in May 2025, with 74% using it on an average day, up from 64% a year earlier. No other messaging service comes close: Facebook Messenger reached 58% monthly and is falling.

For a business it works differently from texting, in three ways.

• Opt-in is required. WhatsApp's policy says you may only message people who have given you their number and opted in to hear from you there.
• The 24-hour window. When a customer messages you, you can reply in ordinary messages for 24 hours. After that you may only send pre-approved templates.
• You pay per message, by type. Marketing, utility and authentication templates each have a price set by Meta for the recipient's country.

Prices changed twice in 2026. The UK marketing rate rose on 1 July. And from 1 October 2026, replies inside the window are no longer free without limit: each business number gets 1,000 free service messages a month and is charged from the 1,001st. Third-party sources put UK rates at about 4.6p for marketing and 1.6p for utility messages, excluding VAT; take the current figures from Meta's own rate card, because several published guides disagree.

WhatsApp is at its best for two-way conversations with people who have chosen it: confirming and rearranging appointments, answering questions about a quote, sending a photo or a document. It also has to offer a route to a person: Meta's policy requires automated services to provide clear escalation paths.

SMS: no app, no opt-in to a platform, no pictures

The claim you will read everywhere is that SMS has a 98% open rate. It can't be true in the way it is stated, because a text message has no tracking pixel and no read receipt: nobody can measure whether it was opened. The figure has circulated since about 2010 with no study behind it.

What can be said for SMS is simpler and still valuable. It arrives on every mobile phone, without an app, an account or a data connection, and sits in an inbox far less crowded than email. That makes it the dependable choice for a short message to someone you have no other channel for.

The practical details:

• Length. A standard text is 160 characters. Longer messages are split into 153-character segments and billed per segment. One emoji or unusual character switches the whole message to a different encoding with a 70-character limit, which can triple the cost.
• Sender name. You can send from your business name, but customers can't reply to a name. For a conversation, or a reply-STOP opt-out, send from a number.
• New rules. Ofcom's July 2026 rules against messaging scams require providers to check business senders and their sender names, taking effect for business messaging on 15 July 2027. Expect more paperwork when you set up a sender name. Ofcom decided against a mandatory sender ID register, whatever some blogs say.

Email: slow, cheap and the only one with room

Email is where detail belongs: the quote, the terms, the confirmation someone will search for in three months. YouGov found it is the single most preferred customer service channel in Britain, chosen by 33%, and its popularity is steady across every age group.

Its weakness is attention. Reported open rates are no longer trustworthy, because Apple's Mail Privacy Protection loads messages automatically and inflates them. Measure replies and clicks instead. And deliverability is real work: the DMA's 2026 benchmark put UK inbox placement at about 91%, which means roughly one email in eleven does not reach the inbox at all.

Use email for what needs space or permanence, and don't rely on it alone for anything time-sensitive.

The phone call: still the one for urgent and complicated

A call resolves in three minutes what takes two days of messages, and for urgent or worrying matters it remains what people want. The difficulty is getting it answered.

Ofcom asked UK adults how likely they were to pick up a call from a UK mobile number they didn't recognise. 51% said unlikely, including 28% very unlikely. For a withheld number it was 60%.

That is stated intention, not measured behaviour, but it points to the obvious remedies: always show a real number people can ring back, call quickly while they are expecting you, and send a text first or straight after. "Hi, it's Sam from Hartley Heating about your boiler enquiry. I just tried to call. When suits?" turns a missed call into a conversation.

Which channel for which job

On reminders there is good trial evidence. A Cochrane review of seven trials found text reminders improved attendance about as much as phone-call reminders, at roughly half the cost or less. That is healthcare, but the logic carries.

Let the customer choose

Averages hide the point. YouGov found the phone was the preferred channel for 50% of the oldest generation and 16% of Gen Z, while live chat was preferred by 15% of Gen Z and 2% of the oldest. Any single channel you pick is the wrong one for a large share of your customers.

Three practical ways to find the right one:

1. Ask. A "how would you like us to contact you?" on the enquiry form is the cheapest research you will ever do.
2. Notice where they reply. If someone ignores two calls and answers a WhatsApp in a minute, carry on there.
3. Fall back in order. When one channel gets no response, move to the next, and stop when they answer.

The second and third only work if every channel is one conversation. If calls live in one system, texts in another and email in a third, nobody can see that the person who didn't pick up has just replied by message. That is the case for one history per person and one inbox.

The rules, briefly

Each channel has its own consent rules in the UK. In outline: live marketing calls must be screened against the Telephone Preference Service; marketing texts and emails to individuals need consent or the soft opt-in; automated marketing calls need specific consent; WhatsApp needs its own opt-in. Service messages about something the customer asked for are treated differently from marketing. One opt-out should stop every channel. The detail is in our guide to the UK rules for AI calls and texts.

One channel is a guess

A fixed, single-channel sequence assumes you already know how each customer wants to be reached. You don't. A journey that starts with the likeliest channel, moves when it gets no answer and stays wherever the customer responds will reach more people with fewer messages. That is the subject of linear sequences versus branching flows.

Questions people ask

Sources

1. Ofcom, Online Nation 2025 report (December 2025). ofcom.org.uk
2. Ofcom, experiences of suspicious calls, texts and app messages (2024). ofcom.org.uk
3. YouGov, a deep dive into British customer service preferences (April 2025). yougov.com
4. Meta, WhatsApp Business Platform pricing. developers.facebook.com
5. WhatsApp Business Messaging Policy (updated September 2026). whatsappbusiness.com
6. Ofcom, new rules to thwart text message scammers (July 2026). ofcom.org.uk
7. Twilio, what is the SMS character limit?. twilio.com
8. ICO, guidance on electronic mail marketing. ico.org.uk
9. Gurol-Urganci et al., mobile phone messaging reminders for attendance at healthcare appointments (Cochrane review, 2013). pubmed.ncbi.nlm.nih.gov
10. Validity, the 2026 DMA email benchmark report. validity.com