With WhatsApp Business growing rapidly in the UK and SMS remaining the backbone of business messaging, many companies face a straightforward question: which channel should we use? The honest answer, for most businesses, is both. But understanding the strengths and limitations of each helps you deploy them effectively.
Reach and accessibility
SMS has a fundamental advantage that no messaging app can match: it works on every mobile phone ever made. There are approximately 95 million active mobile connections in the UK according to Ofcom's 2024 Communications Market Report. Every single one of them can receive an SMS. No smartphone required. No app download. No internet connection.
WhatsApp, by contrast, requires a smartphone, the WhatsApp app installed, and an active internet connection. While around 75% of UK adults use WhatsApp, that still leaves a quarter of the adult population unreachable through the platform — including many older consumers and those in areas with poor connectivity.
Delivery guarantees
SMS messages are delivered via the mobile network, independent of internet availability. If a recipient is in a mobile signal area, the message will arrive. This makes SMS the only viable option for genuinely critical communications: emergency alerts, security codes, and time-sensitive notifications like appointment reminders.
WhatsApp messages require an active data connection. If a recipient is offline, messages queue until they reconnect. For most marketing and support use cases this is acceptable, but for urgent transactional messages it introduces unacceptable uncertainty.
Content and interactivity
This is where WhatsApp shines. WhatsApp Business messages can include images, videos, documents, location pins, interactive buttons, quick replies, and product catalogues. A customer support conversation on WhatsApp feels far richer than a back-and-forth text exchange.
SMS is limited to 160 characters of plain text per segment. While concatenation allows longer messages, there is no native support for media or interactive elements. SMS is concise by design, which is both a constraint and a strength — short messages get read faster.
Cost comparison
SMS is priced per message, typically 2-5p in the UK depending on volume. WhatsApp Business uses conversation-based pricing, where a 24-hour window costs a flat fee regardless of how many messages are exchanged. For single notifications, SMS is usually cheaper. For multi-message support conversations, WhatsApp can be more cost-effective. Check our pricing page for current SMS rates.
Use cases for each channel
Best suited for SMS:
- Two-factor authentication and one-time passwords
- Appointment reminders and confirmations
- Delivery and dispatch notifications
- Emergency alerts and critical notifications
- Communications to broad audiences including non-smartphone users
- Marketing campaigns requiring guaranteed delivery
Best suited for WhatsApp Business:
- Customer support and service conversations
- Product catalogues and visual marketing
- Interactive surveys and feedback collection
- Rich media campaigns with images and video
- Ongoing customer engagement and loyalty programmes
Why many businesses use both
The GSMA's Mobile Economy 2024 report highlights a clear trend toward multi-channel messaging strategies. Businesses that combine SMS and WhatsApp achieve better coverage, higher engagement, and more flexibility than those relying on a single channel.
A practical approach: use SMS as your universal delivery layer for transactional and time-critical messages, and layer WhatsApp on top for richer engagement with customers who prefer it. This ensures no message goes undelivered while offering the best possible experience to each recipient.
Faretext provides the SMS foundation for this multi-channel approach, with direct Tier 1 carrier connections, a robust SMS API, and international coverage across 190+ countries.
Frequently asked questions
Can I send both SMS and WhatsApp messages through Faretext?
Currently, Faretext specialises in SMS messaging via API, SMPP, email-to-SMS, and web application. For businesses exploring WhatsApp alongside SMS, our team can advise on the best multi-channel strategy for your needs.
Which channel has better open rates?
Both channels report open rates above 95%. The key difference is reach — SMS reaches every mobile phone, while WhatsApp requires a smartphone with the app installed and an internet connection.
Should I replace SMS with WhatsApp?
No. SMS and WhatsApp serve different purposes and excel in different scenarios. Replacing SMS with WhatsApp would mean losing the ability to reach the 25% of UK adults who do not use WhatsApp, and sacrificing the guaranteed delivery that SMS provides without internet dependency.
Sources: GSMA Mobile Economy 2024, Ofcom Communications Market Report 2024
