Voice services
Voice calls at scale — OTPs, alerts and campaigns in any language
Reach millions in a day with automated voice calls — verification codes read aloud, critical alerts that can't be missed, and campaigns in your customers' own languages.
Multi-language TTS · Millions of calls/day · Global coverage
What are voice services?
Voice services let software place phone calls the way an SMS API sends texts: your system triggers a call, our platform dials the number, plays a message — text-to-speech or your own recording — and reports the outcome. No call center, no dialer hardware, no telecom contracts.
The channel's superpower is universality with attention. A ringing phone works on every device from the newest smartphone to a landline, needs no internet, and is genuinely hard to ignore — which is why banks call for high-value OTPs and why reminders convert better spoken aloud.
You can run voice standalone or chain it with messaging: SMS first for speed, an automatic voice call when the text isn't delivered — one API call configures the whole flow.
Use cases
What businesses run on voice
Voice is the channel for messages that must be heard — not just delivered.
Voice OTP
Verification codes read aloud — a second factor that works when SMS is delayed or filtered.
Transactional alerts
Payment confirmations, delivery updates and fraud warnings that demand attention.
Reminders
Appointments, EMI due dates and renewals — a call gets acted on more than a text.
Campaigns
Outbound promotions and surveys with key-press responses, throttled to your call-center capacity.
How it works
From script to campaign in four steps
Everything runs from the dashboard or the API — whichever your team prefers.
Create the message
Type it for text-to-speech in your chosen language and voice, or upload a studio recording.
Pick the audience
Upload a list, choose a segment, or trigger calls one-by-one from your backend via API.
Set pacing & retries
Calls per second, retry attempts for no-answers, time windows and key-press options (press 1 to confirm).
Launch and measure
Watch answered, voicemail and no-answer outcomes live; DTMF responses stream to your webhook.
Languages
Spoken in your customer's language
Text-to-speech and pre-recorded prompts in the languages your markets speak.
- English
- Spanish
- French
- German
- Portuguese
- Arabic
- Hindi
- Bahasa
- Mandarin
- Japanese
Need a language you don't see? Ask — the TTS catalogue is much longer than this list.
Comparison
Voice OTP vs SMS OTP
Not a rivalry — a pairing. Most teams send SMS first and fall back to a voice call, or offer “Call me instead” up front.
| Voice OTP | SMS OTP | |
|---|---|---|
| Delivery | Rings through even when SMS routes are congested or filtered | Fast, but silently filtered in some destinations |
| Accessibility | Works for low-literacy users and feature-phone keypads | Requires reading a text |
| Attention | A ringing phone is hard to ignore | Easily missed among notifications |
| Cost | Priced per call — typically above one SMS part | Cheapest unit per attempt |
| Best as | Fallback or user-chosen option | Default first attempt |
Scale
Built for millions of calls a day
Carrier-grade voice infrastructure so the campaign that works at 1,000 calls works at 1,000,000.
Throughput on demand
Concurrent-call capacity that scales with your campaign, with per-second pacing controls.
Answer detection
Human, voicemail or no-answer — each outcome triggers the right retry or fallback logic.
Key-press capture
DTMF responses (“press 1 to confirm”) flow back to your webhook in real time.
Full call records
Per-call status, duration and outcome for reconciliation and analytics.
Pair voice with SMS fallback
The strongest OTP flows chain the channels: SMS first for speed, an automatic voice call when the text isn't delivered or the user asks for it. One API call sets up the whole chain.
FAQ
Voice questions, answered
OTP calls, languages, landlines and how billing works.
What is a voice OTP?
An automated call that reads a one-time password aloud — usually twice — instead of sending it as a text. It's used when SMS is delayed, filtered or inaccessible, and as an accessibility option for users who struggle with texts.
Which languages are supported?
Dozens of languages via text-to-speech, or upload your own recorded prompts for full control over voice and tone. Regional accents are available for major languages.
Is a voice OTP more secure than SMS?
It closes different gaps: voice calls aren't visible on a lock screen, are harder to intercept via SS7 SMS attacks, and confirm liveness (someone answered). Best practice is offering both and letting risk rules or the user decide.
Can I run voice campaigns to landlines?
Yes — voice is the one automated channel that reaches landlines. That matters for demographics and regions where mobile penetration is lower or where landlines are the registered contact.
How are voice calls billed?
Per call, based on duration (per-second or per-minute depending on destination), with rates by country. OTP calls are short and predictable. Volume tiers apply — ask sales for the rate card.
How do retries and consent work for voice campaigns?
Campaigns run only to opted-in numbers within the hours you configure, with retry logic for unanswered calls capped so customers are never harassed. Transactional calls like OTPs deliver around the clock.
Put a voice to your most important messages
Tell us your call volumes and destinations — we'll send the rate card and set up a test campaign.
Global coverage · Volume pricing