Quick comparison
| Criterion | Telegram | SMS | |
|---|---|---|---|
| Public Cascade availability | Yes | Yes | Not yet |
| Cascade cost | 3 credits per successful delivery | 3 credits per successful delivery | 8 credits after public launch |
| Recipient requirement | Access to WhatsApp | Access to Telegram | Mobile network and a supported SMS route |
| Suitable use today | Primary OTP channel | Primary or additional channel | Planned fallback after launch |
| Explicit API choice | channel: whatsapp |
channel: telegram |
Do not use publicly before launch |
This table describes Cascade capabilities on the page update date. It is not a delivery guarantee for every phone number; availability depends on the recipient, company settings, and the external channel.
WhatsApp for OTP
WhatsApp can fit products whose customers already use the app and expect business messages there. The user receives a code in a familiar interface while the product uses the same server-side OTP API.
It is publicly available in Cascade, costs 3 credits per successful delivery, and can carry a code and short link in one message. The limitation is that WhatsApp must be available to the recipient. Do not assume universal access without testing your audience.
Telegram for OTP
Telegram uses the same send and verify flow, so teams can use it as a primary or additional channel according to company settings.
It is publicly available, costs 3 credits per successful delivery, and shares one API integration with WhatsApp. Its practical limitation is recipient access to Telegram. A pilot provides better evidence than general claims about app popularity.
SMS for OTP
SMS does not require a messenger account, so multi-channel designs often consider it as fallback. However, an API field alone does not make a channel publicly available.
Cascade represents SMS technically and configures it at 8 credits after launch. The public SMS provider is currently not connected. Until that changes, product UI and commercial copy must present SMS as planned rather than active fallback.
How to choose
- Define the action: signup, login, recovery, or transaction confirmation.
- Select an available primary channel in company settings.
- Test it with consented numbers from your target audience.
- Measure delivery, time to receive, verification success, and resend.
- Show users only options that actually work.
- Adjust channel order from observed data rather than assumptions.
The backend still uses one Cascade API when a product supports both messengers. See the integration guide for the complete sequence.
Pilot metrics
Measure each channel separately:
- successful delivery rate;
- median delivery time;
- successful verification rate;
- resend volume;
- unavailable-channel errors;
- credits per verified user;
- support contacts.
Do not publish pilot percentages as universal guarantees. One product's result may not transfer to a different audience, market, or verification purpose.
Practical conclusion
WhatsApp and Telegram are the working Cascade choices today. They cost the same and share one API; the meaningful difference is access for a specific recipient. Plan for SMS in future architecture, but do not advertise it as active public fallback before launch.
See current pricing, the POST /otp/send reference, and the documentation for current capabilities.