SMS + RCS + WhatsApp

When it comes to business messaging, selecting the right channel between SMS, WhatsApp for Business and RCS for Business can mean the difference between overlooked outreach, memorable engagement, and missed critical communications.

In an environment of evolving market conditions, regulatory developments, AI and emerging technologies, it’s crucial to understand the use cases of SMS, WhatsApp for Business and RCS for Business (Rich Communication Services) and how these channels stack up in terms of today’s ROI, while building future-ready, secure communications platforms for forward-thinking brands.

Richard Simpson, managing director of Celerity Systems, which incorporates BulkSMS and Kero, says that the debate is not an either/or debate, but rather both/and, which looks at the co-existence between SMS, RCS for Business and WhatsApp for Business in a hybrid model. “SMS, RCS and WhatsApp are all channels that deliver messages to mobile devices, but they differ significantly in terms of features, reach and functionality. SMS retains its role as the trusted channel for mission-critical use cases, universal reach and reliability, while RCS for Business and WhatsApp for Business provide for engagement and interactive customer experiences. It’s about understanding the use case of each and then selecting the best messaging channels.”

SMS: Reach and accessibility

SMS is reliable, universal and ready for urgent messaging. It allows for text messages limited to 160 characters and can include URL links. “SMS is available on virtually every mobile phone worldwide and it requires no apps and requires no internet access. Its simplicity and omnipresence ensure messages land in even the most basic handsets and in areas with the weakest mobile network coverage.”

“For this reason, SMS remains among the most reliable channels in terms of reach and deliverability, and its use case remains strong even in the face of evolving technology. The shift however is towards utility, offering straightforward, text-only delivery that is ideal for time-sensitive alerts like OTPs, authentication, alerts, appointment reminders, service updates or flash promotions where deliverability is key,” explains Simpson.

Realistically, SMS has its limitations in terms of branding and rich media, which means your interaction is limited to plain text and it is harder to track interaction beyond delivery. But this is where the combined use of Rich Business Messaging channels such as WhatsApp for Business and RCS for Business provides the perfect trifecta for communication that is impactful and engaging and always reaches the intended recipient with SMS as failover.

RCS for Business (Rich Communication Services)

RCS for Business is a platform that offers rich interactivity and branding opportunities.

RCS for Business transforms messaging with branding, carousels, images, videos, quick replies and more, that is directly available within the native messaging app. RCS for Business is an evolution of SMS, offering enhanced features and capabilities. While SMS is limited to text, RCS allows for multimedia content, interactive buttons and elements, and richer, engaging customer conversations. RCS for Business applies these capabilities to business-to-customer communications, allowing organisations to engage customers directly within their native messaging app through more dynamic and intuitive conversations.

As a result, read rates soar with 90% of rich media messages opened within 15 minutes. “Though RCS for Business may appear pricier initially for marketing messaging, its engagement and conversion benefits often outweigh the cost increases and are justified for businesses that want to attract attention and greater engagement. It is crucial to implement strategic segmentation and testing to help optimise the ROI,” says Simpson.

One of the most significant advantages of RCS for Business is verified sender identity. Unlike standard SMS, where it is sometimes unclear who sent the message, RCS for Business requires that every sending brand undergoes a rigorous vetting process by Google and the participating mobile network operators before they can send a single message.

Once verified, the brand's name, logo, and a trusted verification badge appear directly in the message thread, so recipients know immediately and with certainty who they are engaging with. This dramatically reduces the risk of phishing and smishing attacks, cuts through the noise of spam, and gives consumers the confidence to engage, click, and transact, making RCS for Business a safer and more credible communication channel.

RCS for Business is available on many feature phones and smartphones and other mobile devices, however, the device message app on these devices needs to be RCS-enabled. RCS for Business is also not yet universally available across all geographies, and its availability still depends on a combination of factors including the country, the mobile network operators, and device and app support.

While RCS for Business as a channel is expanding globally, any business looking to deploy RCS at scale should assess country-by-country availability and work with a messaging partner like Kero that can confirm live carrier coverage and advise on appropriate fallback channels, such as SMS or WhatsApp, where RCS for Business is not yet supported. Kero is a specialist messaging provider that helps businesses reach customers across WhatsApp, RCS and SMS from one simple platform.

WhatsApp for Business

The business API (application programming interface) utilised in WhatsApp is secure, global and adaptable. “With over two billion users globally, WhatsApp offers a secure channel for both iOS and Android users. It excels in centralised message delivery and is widely available in most markets where the WhatsApp app is a popular personal messaging channel,” Simpson explains.

WhatsApp is an 'over-the-top' application which means that it delivers messaging over the internet, on top of the existing mobile or broadband network, rather than through the mobile operator’s traditional SMS or voice systems. Essentially, the mobile network just provides the data connection, and WhatsApp rides over that connection to deliver the service.

End-to-end encryption ensures secure exchanges, making WhatsApp ideal for sensitive conversations. “WhatsApp’s API allows seamless integration with CRMs and SMS, but you do need to consider that it is tied to opt-in, and template restrictions for outbound messaging do limit flexibility while messaging costs vary, particularly for large-scale promotional use. WhatsApp for Business API is best for building strong customer relationships, providing personalised support, and reaching a specific target audience,” Simpson adds.

With verified branding that builds trust and personalised customer engagement, WhatsApp Business provides rich media support with images, videos, and documents for more engaging interactions. With smart fallback options between RCS, SMS and WhatsApp, messages will get delivered if devices don’t support WhatsApp.

Maximising ROI with a smart hybrid channel mix

Adopting a layered approach by means of a smart channel mix plays on the strengths offered by all three of these channels:

• SMS is ideal for universal, reliable alerts. Think security tokens, billing reminders, alerts, authentication or urgent notifications.

• WhatsApp for Business is best for secure, personalised support and flows, which is ideal in the application of customer service, confirmations or follow-up.

• RCS for Business is the most engaging channel for marketing, which is perfect for interactive campaigns, rich promotions and immersive experiences.

As one practical example, appointment reminders are one of the most widely adopted use cases in business messaging, and SMS remains the backbone of this application. Its universal reach makes it indispensable in contexts where smartphone penetration and data connectivity cannot be assumed – rural clinics for example, rely on SMS to reliably reach patients regardless of device type or network quality, ensuring critical healthcare appointments are not missed.

However, WhatsApp for Business and RCS for Business build meaningfully on this foundation by introducing a richer, more interactive experience. Both channels support bot integrations that can handle reminders at scale without human intervention, and critically, they enable customers to take action directly within the message itself – confirming, cancelling, or rescheduling an appointment with a single button tap rather than having to make a call or send a reply.

This reduces no-show rates, eases the administrative burden on staff, and delivers a noticeably more convenient experience for the customer. The result is a tiered approach to appointment communication: SMS ensures no one is left unreached, while WhatsApp and RCS elevate the experience for connected audiences who expect more than a one-way notification.

"RCS for Business offers rich experiences that dramatically boost engagement – especially where supported while WhatsApp for Business provides unmatched global reach, trust and automation. SMS remains the foundation that offers fast, reliable and irreplaceable broad-based delivery regardless of internet connectivity or device. The most savvy businesses will use all three – leveraging each channel’s strengths to optimise engagement, conversions, customer satisfaction and most crucially, return on investment,” Simpson concludes.