Quick Reference

Call API Cheatsheet

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POST/v1/call/otp

Send an OTP via voice call. The recipient receives a call with each digit spoken individually.

Base URL
https://APIURL.tetrax.in/v1

Authentication

API Key Type
trx_call_*
Header
x-api-key: trx_call_your_key

cURL Example

curl -X POST https://APIURL.tetrax.in/v1/call/otp \
  -H "Content-Type: application/json" \
  -H "x-api-key: trx_call_key" \
  -d '{
    "phone": "+919876543210",
    "otp": "4324"
  }'

Success Response

{
  "success": true,
  "callId": "call_1712345678",
  "message": "OTP voice call initiated",
  "call": {
    "id": 1,
    "phone": "+919876543210",
    "otp": "4324",
    "status": "initiated",
    "called_at": "2026-07-23T12:00:00Z"
  }
}

Request Parameters

FieldTypeDescription
phonestringRecipient number with country code
otpstring3–10 digit numeric OTP

Node.js

const response = await fetch(
  "https://APIURL.tetrax.in/v1/call/otp",
  {
    method: "POST",
    headers: {
      "x-api-key": process.env.TETRAX_KEY,
      "Content-Type": "application/json"
    },
    body: JSON.stringify({
      phone: "+919876543210",
      otp: "4324"
    })
  }
);
const data = await response.json();

Python

import httpx

response = httpx.post(
    "https://APIURL.tetrax.in/v1/call/otp",
    headers={"x-api-key": API_KEY},
    json={"phone": "+919876543210", "otp": "4324"}
)
data = response.json()

Webhook Payload

{
  "call_id": "call_1712345678",
  "status": "completed",
  "duration": 45
}
Statuses: initiated, ringing, answered, completed, failed, busy, no-answer

Error Codes

400Bad RequestInvalid phone or OTP format
401UnauthorizedMissing or invalid API key
403ForbiddenWrong API key type (need trx_call_)
429Rate LimitToo many requests — check Retry-After header
402Insufficient BalanceTop up your prepaid wallet
502Bad GatewayProvider error — retry the request

Pricing — Pay As You Go

₹0.28/callper OTP call

One flat price for every account — deducted from your prepaid wallet in real time. No subscriptions, no monthly fees. Rate limits are configured per account.

OTP Verification Flow

1

User enters phone

2

Backend generates OTP

3

Call Tetrax API

4

User hears OTP on call

5

User types OTP in app

6

Backend verifies ✓

Environment Setup

# Store API key securely
TETRAX_CALL_API_KEY=trx_call_xxx

Important Links

Dashboardtetrax.in/dashboard
Full Docstetrax.in/docs/call
Setup Guidetetrax.in/docs/call/setup-guide
API Playgroundtetrax.in/services/call
Call Historytetrax.in/logs/call
Analyticstetrax.in/analytics/call

Tetrax CPaaS — Complete docs at tetrax.in/docs/call | Support: support@tetrax.in

Generated July 2026 — Subject to change. Always refer to online docs for latest version.