WhatsApp vs SMS for Business: Which Should UK Small Businesses Use?
Which channel to use for each message a UK small business sends, what each costs after Meta's October 2026 price change, who each one reaches, and how to run both from one number.
Simon
Updated · 7 min read
The short answer
- Use SMS when the message must reach everyone. Reminders, confirmations, replies to missed calls, and login codes. It reaches every UK mobile with no app and no data.
- Use WhatsApp when the customer wants a conversation. Quotes, job updates, and anything with photos, documents, or voice notes.
- Most businesses need both. Let the customer pick the channel, and answer both from one inbox.
- WhatsApp prices change on 1 October 2026. Replies inside the 24-hour window stop being free.
Back to the complete WhatsApp guide
Which channel for which message
Find the message you send most often. The right channel is in the second column.
| The message | Use | Why |
|---|---|---|
| Appointment reminder | SMS | Reaches every customer, including those without WhatsApp. No template approval needed. |
| Reply to a missed call | SMS | The caller has a mobile you can text now. On WhatsApp you would need an approved template and their opt-in. |
| Booking or order confirmation | SMS or WhatsApp | Either works. Use the channel the customer booked on. |
| Quote with photos or a PDF | SMS carries text only on UK business numbers. | |
| Customer sends a photo of the problem | A leaking pipe or a damaged car is easier to see than to describe. | |
| Ongoing job updates with someone who messaged you on WhatsApp | The conversation is already there, with its history. | |
| Promotion or offer | Either, with consent | SMS reaches more people. WhatsApp costs more per message and needs an approved marketing template. |
| Login or verification code | SMS | Works on any phone, with no app. |
| Customer with no smartphone or no signal | SMS | WhatsApp needs a smartphone and a data connection. |
How WhatsApp and SMS compare
| Feature | SMS | |
|---|---|---|
| Who can receive it | People with a smartphone and the app installed | Every mobile phone |
| Needs data or Wi-Fi | Yes | No. Mobile signal is enough |
| Photos, documents, voice notes | Yes | No. Text only |
| Who can start the conversation | The customer, or you with an approved template after they opt in | Either side, any time |
| Free-form replies | Within 24 hours of the customer’s last message | Any time |
| Long messages | One message, one charge | Split every 153 characters, each part charged |
| Read receipts | Yes | No |
| What the customer sees | Your business name and profile | Your number or a sender name |
The row that matters most is who can start the conversation. SMS lets you text any customer at any time for a service reason. WhatsApp puts the customer in control: you reply freely for 24 hours after they message you, and after that you need a template Meta has approved.
What each channel costs in the UK
SMS costs the same whoever you text and whenever you text them. You pay per segment: one segment carries 160 characters, and a longer message splits into parts of 153 characters, each charged as one text. An emoji switches the whole message to a shorter limit of 70 characters.
WhatsApp costs depend on what kind of message you send and whether the customer messaged you first. Meta charges per message and publishes its UK rates in its pricing documentation. At September 2026 the UK rates are about:
| WhatsApp message type | Example | Meta's UK fee |
|---|---|---|
| Service reply, inside the 24-hour window | Answering a customer's question | Free until 30 September 2026, then the utility rate |
| Utility template | Booking confirmation, job update | About 1.6p |
| Authentication template | Login code | About 2p to 3p |
| Marketing template | Offer or promotion | About 4.6p |
| Any message in a 72-hour free entry window | Reply to someone who tapped a click-to-WhatsApp ad | Free |
Meta publishes its rates in US dollars, and the figures above are converted to pence. The UK marketing rate went up on 1 July 2026, and service replies are charged from 1 October 2026.
Free WhatsApp replies end on 1 October 2026
Since November 2024, Meta has not charged for replies inside the 24-hour customer service window. From 1 October 2026 it does, at the same rate as a utility message. If you chose WhatsApp because customer service was free, check your volumes against the new rate.
The WhatsApp Business app has no per-message fee. It runs on one phone plus a few linked devices, has no shared team inbox, and cannot connect to your other tools. For the full breakdown, read WhatsApp Business pricing in the UK and WhatsApp Business app vs API.
On Line, SMS and WhatsApp messages bill from the same credit balance. The current rate for each is on the pricing page.
Who each channel reaches
WhatsApp reaches most of your customers. Ofcom's Online Nation 2025 report found that 90% of UK online adults used WhatsApp in 2025, and 74% used it every day.
SMS reaches all of them. Ofcom's Technology Tracker 2025 found that 92% of UK adults use a smartphone, so about one adult in twelve cannot receive a WhatsApp message at all. A text also arrives with no data signal, which matters in rural areas and on building sites.
In practice: if a message must arrive, send a text. If the customer has already chosen WhatsApp, reply there.
The rules: consent and the 24-hour window
Service messages need no marketing consent on either channel. The ICO treats a message that only responds to a customer, or tells them about their booking or order, as a service message. Keep offers out of these messages.
Marketing needs consent on both. PECR applies to WhatsApp as it does to SMS. Every marketing text needs a way to opt out, such as "Reply STOP". See the SMS marketing compliance guide and the WhatsApp GDPR guide.
WhatsApp adds its own rules on top.
- The customer must opt in before you message them first on WhatsApp.
- A business-started message must use a template that Meta has approved.
- Free-form replies are allowed for 24 hours after the customer's last message. Each new message from the customer restarts the 24 hours.
Examples by business type
- Trades. Ask for a photo of the fault on WhatsApp before you visit. Send the "on my way" text by SMS, so it arrives even if the customer's data is off. See Line for tradespeople and WhatsApp for tradespeople.
- Salons and barbers. Send appointment reminders by SMS. Take style photos and rebooking chats on WhatsApp. See Line for salons and barbers.
- Clinics and practices. Keep automatic reminders to SMS with no clinical detail. See Line for clinics and practices.
- Estate agents. Send viewing confirmations by SMS. Share floor plans and photos with interested buyers on WhatsApp. See Line for estate agents.
Running both from one number and one inbox
Using both channels used to mean two apps, two phones, and nobody sure who replied. Line puts them together.
- One UK business number for calls and texts. Connect WhatsApp to the same number, or keep the WhatsApp Business number you already use.
- One shared inbox for SMS, WhatsApp, and calls, so the whole team sees every conversation.
- The 24-hour window is tracked for you. Line shows when a free-form reply is allowed and when you need a template. See the WhatsApp Business API page.
- A missed call becomes a text. Missed-call text back replies by SMS, which reaches every caller.
- AI agents answer on both channels, so a customer gets a reply while the team is busy.
Back to the complete WhatsApp guide
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