Short answerUse SMS when the message must arrive no matter what: it reaches every mobile phone and needs no app and no internet connection. Use WhatsApp when the message benefits from images, buttons or a real conversation, and you know the customer uses it. Most businesses need both.
| SMS | WhatsApp Business API | |
|---|---|---|
| Reach | Every mobile phone on earth | Only users with the app installed |
| Needs internet | No | Yes |
| Length | 160 characters per segment (70 for Arabic and other non-Latin scripts) | Long-form |
| Rich content | Text only | Images, documents, buttons, lists |
| Two-way | Limited | Full conversation |
| Before you can send | Sender ID registration | Template approval by Meta |
| Cost | Higher per message in most markets | Lower in most markets |
| Best for | OTP, critical alerts, universal fallback | Support, rich notifications, marketing |
WhatsApp usually costs less per message, but it only reaches people who have the app and an internet connection at that moment. A cheaper message that does not arrive is not cheaper.
WhatsApp also gates who may start a conversation. Outside a 24-hour window opened by the customer, you can only send content Meta has pre-approved as a template. SMS has no such restriction on the message itself.
No, and choosing is usually the wrong instinct. Cascaded messaging sends the same message to WhatsApp first and falls back to SMS only when WhatsApp does not confirm delivery, so you get WhatsApp's economics and SMS's reach in one API call and pay only for the attempt that lands.
Ritorica Cascaded Messaging tries the cheaper channel first and falls back automatically.
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