At Prelude, we believe verification should feel seamless for users and efficient for teams.

That’s why we’ve added a new capability to give you more control over how your OTPs reach users: Preferred Channel Routing.

Whether you send codes via SMS, WhatsApp, Telegram, Viber, or Voice, you can now guide the delivery channel without giving up flexibility or fallback reliability.

Why Channel Choice Matters

The most effective delivery channel depends on context. For example:

• SMS may be unreliable or expensive in some regions

• Voice can be more effective for older audiences

• WhatsApp or Telegram may appeal to users who value privacy or convenience

Preferred Channel Routing gives you the ability to define your first-choice channel with a simple API parameter. Prelude handles the rest behind the scenes.

How It Works

When initiating a verification, just specify your preferred channel using the preferred_channel option:

json
CopierModifier
{
  "target": {
    "type": "phone_number",
    "value": "+30123456789"
  },
  "options": {
    "preferred_channel": "whatsapp"
  }
}

If the requested channel is supported and available, it is used. If not, Prelude automatically chooses the next best option based on real-time delivery conditions.

This gives you control without sacrificing reliability.

Available Channels (June 2025)

You can choose from:

• SMS

• WhatsApp

• Telegram (new)

• Viber

• RCS

• Voice OTP

• Zalo (available in Vietnam only)

All channels are supported through Prelude’s network of direct connections with carriers and messaging providers.

More channels are coming soon as we continue expanding support based on customer needs and global usage trends.

Control delivery logic from the dashboard

Not a developer? You can set up routing preferences for each country directly in the Prelude Dashboard.

• Decide which channels are allowed per market

• Set fallback strategies (e.g., cost-first, conversion-first, or balanced)

• View delivery success by channel and iterate fast

Built for Smart Defaults

Even with a preferred channel selected, Prelude’s routing engine still evaluates real-time conditions, including:

• Local delivery success rates

• Provider-level costs

• Message latency and retry behavior

• Device and OS signals

This keeps your verification flow fast, reliable, and optimized at all times.

A Better UX by Default

If your product supports multiple delivery channels, users benefit too. They can seamlessly retry over WhatsApp, Telegram, or Viber. Here's what that looks like in the product interface:

Designed for Real-World UX

If your app supports multiple channels for code delivery, users can seamlessly retry over WhatsApp, Telegram, or Viber — just like in the interface below:

Optimize Your Verification Flow Now

Preferred Channel Routing is now available for all Prelude customers through both the API and the Dashboard.

If you care about improving conversion rates, reducing costs, or delivering a smoother user experience, this feature helps you do all three.

Log in to your Prelude Dashboard or visit the API docs to get started.