International Voice: Voice Fallback When SMS Cannot Reach

When OTPs are blocked or SMS is unavailable, voice OTP and notification calls provide reliable reach for high-security scenarios.

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International voice is suited to financial risk control, account security, and high-priority notifications. When SMS routes are congested or blocked, voice can serve as a fallback channel. It supports Voice OTP, TTS notifications, and agent-assisted outbound calls.

Core Capabilities

Every capability is validated in real production environments.

Voice OTP

Users hear the OTP by answering a call, avoiding dependency on SMS routes when messages are blocked or delayed.

Text-to-speech (TTS)

Automatically converts text into voice announcements without prerecorded audio, enabling multilingual notifications quickly.

Notification calls

Proactively call users for order confirmation, appointment reminders, or satisfaction surveys.

SMS fallback complement

Use with international SMS so voice calls trigger automatically when SMS fails.

Multilingual announcements

Supports multilingual TTS engines and can select the right language by user region.

Call records and receipts

Connection status, call duration, and user interaction records are returned for tracking and audit.

Use Cases

See which scenarios best fit your business.

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Financial-grade identity verification

For bank onboarding, high-value transfers, and password resets, voice OTP helps keep verification secure.

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Medical appointment reminders

Call patients before appointments to reduce no-shows and improve resource utilization.

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Logistics delivery confirmation

Call users before delivery to confirm time and location, reducing redelivery and improving completion rates.

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Satisfaction follow-up

Automatically call users after service completion for satisfaction scoring, with responses returned to the business system.

How to Get Started

Get up and running in just a few steps.

Define the scenario

Tell us whether you need voice OTP, TTS notifications, or outbound calls, plus target markets and languages.

Configure routes

Configure the best voice routes by target country to protect connection rates and audio quality.

API integration

Integrate voice capabilities through standard APIs with status callbacks.

Launch monitoring

Monitor connection rates and call quality after launch, then optimize route strategy.

Coverage & Access

Voice routes in major markets with multilingual TTS support

Frequently Asked Questions

Common questions about this product. Contact us if you need more help.

What is the difference between voice OTP and SMS OTP?

Voice OTP reads the code over a phone call and does not rely on SMS routes, making it a reliable fallback when SMS is blocked or delayed.

Which languages are supported by the voice service?

TTS is available in Chinese, English, Japanese, Korean, Spanish, French, Arabic, and more than a dozen languages.

How should voice OTP and SMS OTP be used together?

Use SMS as the primary channel and voice as automatic fallback. If SMS fails or is not received in time, the system triggers a voice OTP call to balance cost and critical delivery.

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Share your use case and get a free integration proposal.

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