SMS, Viber and Email are not competitors, they are complementary tools. The question is not "which one is best" but "which one fits each message". Let's compare them.
Comparison at a glance
| Criterion | SMS | Viber | |
|---|---|---|---|
| Open rate | ~98% | High | ~20% |
| Time to read | Minutes | Minutes | Hours |
| Rich content | Text | Images, buttons, carousel | Full HTML |
| Internet | No | Yes | Yes |
| Cost/message | Low | Very low | Minimal |
| Ideal for | Notifications, OTP | Promotions with images | Newsletters, in-depth content |
SMS: immediacy & universal reach
SMS is almost always read, and read immediately, and it works on every mobile phone without internet. Ideal for urgent notifications, OTP codes, reminders and time-sensitive offers. See SMS campaigns.
Viber: rich content at a low cost
When you want to showcase products with images, CTA buttons or a carousel, Viber comes out ahead, often at a cost lower than SMS and with seen reports. Ideal for promotional campaigns for online stores.
Email: depth & storytelling
Email remains unbeatable for detailed content: newsletters, educational material, receipts. A lower open rate, but unlimited space and minimal cost.
How to combine them
The strongest strategy is the combination: for example, email for the detailed newsletter, Viber for the promotional campaign with images, and SMS for the urgent reminder or the OTP. With automations you define which channel is triggered in each situation.
Conclusion
Do not pick one channel, pick the right channel for each message. SMS for immediacy, Viber for rich promotions, email for depth. A unified platform such as iSend lets you manage them all together.