Telvera / Docs

Phone verification by incoming call: requests, responses, webhooks

Base URL https://api.telvera.io

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Overview

Telvera confirms a phone number with an incoming call instead of an SMS code. You show the user a number, they call it from their phone, we drop the call without answering (free for the user) and tell your server that the number is verified.

The API is two requests and a webhook:

  1. POST /v1/verify — send the user's number, get call_to, the number they should call.
  2. The user calls call_to from their phone.
  3. We send the verification.verified webhook (or you check the status with GET /v1/verify/{id}).

Requests and responses are JSON, times are ISO 8601 in UTC, phone numbers in responses are E.164.

Quick start

1. Get a key in the dashboard: “Settings → API”. Send it in the Authorization: Bearer sk_live_… header. Keep it on your server only.

2. Request a number to call:

curl https://api.telvera.io/v1/verify \
  -H "Authorization: Bearer $TELVERA_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: signup-7f3c2a" \
  -d '{"phone": "+375290000001"}'
<?php
$ch = curl_init('https://api.telvera.io/v1/verify');
curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => [
        'Authorization: Bearer ' . getenv('TELVERA_API_KEY'),
        'Content-Type: application/json',
        'Idempotency-Key: signup-' . $sessionId,
    ],
    CURLOPT_POSTFIELDS     => json_encode(['phone' => '+375290000001']),
]);
$body = json_decode(curl_exec($ch), true);
$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);

if ($status >= 400) {
    throw new RuntimeException($body['error']['code'] ?? 'http_' . $status);
}
echo $body['call_to']; // show it to the user
const response = await fetch('https://api.telvera.io/v1/verify', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.TELVERA_API_KEY}`,
    'Content-Type': 'application/json',
    'Idempotency-Key': `signup-${sessionId}`,
  },
  body: JSON.stringify({ phone: '+375290000001' }),
});
const body = await response.json().catch(() => ({})); // a proxy may return HTML
if (!response.ok) throw new Error(body.error?.code ?? `http_${response.status}`);

console.log(body.call_to); // show it to the user
import os
import requests

response = requests.post(
    "https://api.telvera.io/v1/verify",
    headers={
        "Authorization": f"Bearer {os.environ['TELVERA_API_KEY']}",
        "Idempotency-Key": f"signup-{session_id}",
    },
    json={"phone": "+375290000001"},
    timeout=10,
)
response.raise_for_status()  # 4xx/5xx raises; the error code is response.json()["error"]["code"]
verification = response.json()

print(verification["call_to"])  # show it to the user
using System.Net.Http.Json;
using System.Text.Json;

using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization = new("Bearer", Environment.GetEnvironmentVariable("TELVERA_API_KEY"));

var request = new HttpRequestMessage(HttpMethod.Post, "https://api.telvera.io/v1/verify")
{
    Content = JsonContent.Create(new { phone = "+375290000001" }),
};
request.Headers.Add("Idempotency-Key", $"signup-{sessionId}");
var response = await http.SendAsync(request);
var body = await response.Content.ReadFromJsonAsync<JsonElement>();
if (!response.IsSuccessStatusCode)
    throw new Exception(body.GetProperty("error").GetProperty("code").GetString());

Console.WriteLine(body.GetProperty("call_to").GetString()); // show it to the user
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

var request = HttpRequest.newBuilder(URI.create("https://api.telvera.io/v1/verify"))
    .header("Authorization", "Bearer " + System.getenv("TELVERA_API_KEY"))
    .header("Content-Type", "application/json")
    .header("Idempotency-Key", "signup-" + sessionId)
    .POST(HttpRequest.BodyPublishers.ofString("{\"phone\": \"+375290000001\"}"))
    .build();
var response = HttpClient.newHttpClient().send(request, HttpResponse.BodyHandlers.ofString());
if (response.statusCode() >= 400) throw new RuntimeException(response.body());

String json = response.body(); // the body is JSON with call_to; parse it with Jackson or Gson
req, _ := http.NewRequest("POST", "https://api.telvera.io/v1/verify",
	strings.NewReader(`{"phone": "+375290000001"}`))
req.Header.Set("Authorization", "Bearer "+os.Getenv("TELVERA_API_KEY"))
req.Header.Set("Content-Type", "application/json")
req.Header.Set("Idempotency-Key", "signup-"+sessionID)

resp, err := http.DefaultClient.Do(req)
if err != nil {
	log.Fatal(err)
}
defer resp.Body.Close()

var v struct {
	ID     string `json:"id"`
	CallTo string `json:"call_to"`
	Error  struct{ Code string `json:"code"` } `json:"error"`
}
json.NewDecoder(resp.Body).Decode(&v)
if resp.StatusCode >= 400 {
	log.Fatalf("telvera: %d %s", resp.StatusCode, v.Error.Code)
}
fmt.Println(v.CallTo) // show it to the user
require "net/http"
require "json"

response = Net::HTTP.post(URI("https://api.telvera.io/v1/verify"), { phone: "+375290000001" }.to_json,
  "Authorization" => "Bearer #{ENV.fetch("TELVERA_API_KEY")}", "Content-Type" => "application/json",
  "Idempotency-Key" => "signup-#{session_id}")
body = JSON.parse(response.body) rescue {}
raise "telvera: #{body.dig("error", "code") || response.code}" unless response.is_a?(Net::HTTPSuccess)

puts body["call_to"] # show it to the user
Response · 201 Created
{
  "id": "vrf_0d9a3d2b5ca2439b9af861470d5986bc",
  "status": "pending",
  "phone": "+375290000001",
  "call_to": "+375170000002",
  "expires_at": "2026-10-08T15:39:13Z",
  "verified_at": null,
  "metadata": null,
  "created_at": "2026-10-08T15:38:13Z"
}

3. Show call_to to the user — as a tel: button on mobile, as a QR code on desktop — with a countdown to expires_at.

4. Get the result. Set a webhook URL on the key in the dashboard — after the call it receives verification.verified; verify its signature. Without a webhook, poll GET /v1/verify/{id} every 2–3 seconds while the status is pending.

Reference

The verification object

Both methods return a verification, and the webhook carries it in data.

idstring
Identifier: vrf_ followed by 32 hex characters
statusstring
pending — waiting for the call, verified — number confirmed, expired — no call came
phonestring
The user's number, E.164
call_tostring
The number the user should call, E.164
expires_atstring
Until when we wait for the call: one minute after creation
verified_atstring | null
When the call was counted
metadataobject | null
Your data from the request, unchanged: same object, same value types
created_atstring
When it was created

verified and expired are final. A call made in time may reach us with a delay, so for another 35 seconds after expires_at the verification stays pending and can still be confirmed — unless you create a new one for this number in the meantime.

The verification object
{
  "id": "vrf_0d9a3d2b5ca2439b9af861470d5986bc",
  "status": "pending",
  "phone": "+375290000001",
  "call_to": "+375170000002",
  "expires_at": "2026-10-08T15:39:13Z",
  "verified_at": null,
  "metadata": { "user_id": "42" },
  "created_at": "2026-10-08T15:38:13Z"
}

Create a verification

POST/v1/verify

Returns the number the user should call — they have one minute. A check is taken from your package only when the status becomes verified.

Body parameters

phonestringrequired
The user's number in international format; spaces, brackets and dashes are fine. Missing or unrecognised — invalid_phone
metadataobject
A flat object of up to 20 fields. Key — a string up to 64 characters; value — a string up to 500 characters, a number, true/false or null. Returned in responses and the webhook
Idempotency-Keyheader
Retry key — one per user session/attempt, e.g. signup-<session id>. A repeat with the same key returns the same verification. 1–255 printable ASCII characters

Returns

201 Created and a new verification with status pending. A repeat with the same Idempotency-Key — 200 OK, header Idempotent-Replayed: true and the same verification.

Errors

HTTP code When
401 unauthorized The key is missing, wrong or revoked
402 insufficient_checks No checks left in your package
403 account_disabled The account is blocked
403 test_phone_only Test key with someone else's number
422 invalid_phone phone is missing or not recognised
422 phone_not_supported Numbers of this country aren't supported yet — retrying won't help
422 idempotency_key_reused The same Idempotency-Key was already used with another number
422 invalid_request The body is not JSON, metadata is not a flat object or has more than 20 fields
429 rate_limited More than 120 requests per minute per key, or more than 5 new verifications of the same number per 10 minutes
503 unavailable No free number right now; retry after Retry-After seconds

Retries. Send an Idempotency-Key tied to the user's session. A repeat with the same key within 24 hours (double click, network failure) returns the same verification — nothing is charged and the limit isn't used. Without a key, every request creates a new verification: we don't detect repeats by phone number, otherwise another session could get your verification.

Another number. If the user couldn't get through, create the verification again with a new key. You get a different call_to, and the previous verification becomes expired right away (with a webhook); calls to its number no longer count.

curl https://api.telvera.io/v1/verify \
  -H "Authorization: Bearer $TELVERA_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: signup-7f3c2a" \
  -d '{"phone": "+375290000001", "metadata": {"user_id": "42"}}'
<?php
$ch = curl_init('https://api.telvera.io/v1/verify');
curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => [
        'Authorization: Bearer ' . getenv('TELVERA_API_KEY'),
        'Content-Type: application/json',
        'Idempotency-Key: signup-' . $sessionId,
    ],
    CURLOPT_POSTFIELDS     => json_encode(['phone' => '+375290000001', 'metadata' => ['user_id' => '42']]),
]);
$body = json_decode(curl_exec($ch), true);
if (curl_getinfo($ch, CURLINFO_HTTP_CODE) >= 400) {
    throw new RuntimeException($body['error']['code']);
}
const response = await fetch('https://api.telvera.io/v1/verify', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.TELVERA_API_KEY}`,
    'Content-Type': 'application/json',
    'Idempotency-Key': `signup-${sessionId}`,
  },
  body: JSON.stringify({ phone: '+375290000001', metadata: { user_id: '42' } }),
});
const body = await response.json().catch(() => ({})); // a proxy may return HTML
if (!response.ok) throw new Error(body.error?.code ?? `http_${response.status}`);
import os
import requests

response = requests.post(
    "https://api.telvera.io/v1/verify",
    headers={
        "Authorization": f"Bearer {os.environ['TELVERA_API_KEY']}",
        "Idempotency-Key": f"signup-{session_id}",
    },
    json={"phone": "+375290000001", "metadata": {"user_id": "42"}},
    timeout=10,
)
response.raise_for_status()
verification = response.json()
using System.Net.Http.Json;
using System.Text.Json;

using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization = new("Bearer", Environment.GetEnvironmentVariable("TELVERA_API_KEY"));

var request = new HttpRequestMessage(HttpMethod.Post, "https://api.telvera.io/v1/verify")
{
    Content = JsonContent.Create(new { phone = "+375290000001", metadata = new { user_id = "42" } }),
};
request.Headers.Add("Idempotency-Key", $"signup-{sessionId}");
var response = await http.SendAsync(request);
var body = await response.Content.ReadFromJsonAsync<JsonElement>();
if (!response.IsSuccessStatusCode)
    throw new Exception(body.GetProperty("error").GetProperty("code").GetString());
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

var request = HttpRequest.newBuilder(URI.create("https://api.telvera.io/v1/verify"))
    .header("Authorization", "Bearer " + System.getenv("TELVERA_API_KEY"))
    .header("Content-Type", "application/json")
    .header("Idempotency-Key", "signup-" + sessionId)
    .POST(HttpRequest.BodyPublishers.ofString("{\"phone\": \"+375290000001\", \"metadata\": {\"user_id\": \"42\"}}"))
    .build();
var response = HttpClient.newHttpClient().send(request, HttpResponse.BodyHandlers.ofString());
if (response.statusCode() >= 400) throw new RuntimeException(response.body());

String json = response.body(); // the body is JSON with call_to; parse it with Jackson or Gson
req, _ := http.NewRequest("POST", "https://api.telvera.io/v1/verify",
	strings.NewReader(`{"phone": "+375290000001", "metadata": {"user_id": "42"}}`))
req.Header.Set("Authorization", "Bearer "+os.Getenv("TELVERA_API_KEY"))
req.Header.Set("Content-Type", "application/json")
req.Header.Set("Idempotency-Key", "signup-"+sessionID)

resp, err := http.DefaultClient.Do(req)
if err != nil {
	log.Fatal(err)
}
defer resp.Body.Close()

var v struct {
	ID     string `json:"id"`
	CallTo string `json:"call_to"`
	Error  struct{ Code string `json:"code"` } `json:"error"`
}
json.NewDecoder(resp.Body).Decode(&v)
if resp.StatusCode >= 400 {
	log.Fatalf("telvera: %d %s", resp.StatusCode, v.Error.Code)
}
require "net/http"
require "json"

response = Net::HTTP.post(URI("https://api.telvera.io/v1/verify"), { phone: "+375290000001", metadata: { user_id: "42" } }.to_json,
  "Authorization" => "Bearer #{ENV.fetch("TELVERA_API_KEY")}", "Content-Type" => "application/json",
  "Idempotency-Key" => "signup-#{session_id}")
body = JSON.parse(response.body) rescue {}
raise "telvera: #{body.dig("error", "code") || response.code}" unless response.is_a?(Net::HTTPSuccess)
Response · 201 Created
{
  "id": "vrf_0d9a3d2b5ca2439b9af861470d5986bc",
  "status": "pending",
  "phone": "+375290000001",
  "call_to": "+375170000002",
  "expires_at": "2026-10-08T15:39:13Z",
  "verified_at": null,
  "metadata": { "user_id": "42" },
  "created_at": "2026-10-08T15:38:13Z"
}

Get status

GET/v1/verify/{id}

Returns the verification with its current status. Poll no more than once every 2 seconds while the status is pending; for high volume, use the webhook.

Path parameters

idstringrequired
The verification ID from the POST /v1/verify response

Returns

200 OK and a verification object.

Errors

HTTP code When
401 unauthorized The key is missing, wrong or revoked
403 account_disabled The account is blocked
404 not_found No such verification, or it belongs to another account
429 rate_limited More than 3000 status requests per minute per key
curl https://api.telvera.io/v1/verify/vrf_0d9a3d2b5ca2439b9af861470d5986bc \
  -H "Authorization: Bearer $TELVERA_API_KEY"
<?php
$ch = curl_init('https://api.telvera.io/v1/verify/' . $verificationId);
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . getenv('TELVERA_API_KEY')],
]);
$body = json_decode(curl_exec($ch), true);
if (curl_getinfo($ch, CURLINFO_HTTP_CODE) >= 400) {
    throw new RuntimeException($body['error']['code']);
}
const response = await fetch(`https://api.telvera.io/v1/verify/${verificationId}`, {
  headers: { Authorization: `Bearer ${process.env.TELVERA_API_KEY}` },
});
const body = await response.json().catch(() => ({})); // a proxy may return HTML
if (!response.ok) throw new Error(body.error?.code ?? `http_${response.status}`);
import os
import requests

response = requests.get(
    f"https://api.telvera.io/v1/verify/{verification_id}",
    headers={"Authorization": f"Bearer {os.environ['TELVERA_API_KEY']}"},
    timeout=10,
)
response.raise_for_status()
verification = response.json()
using System.Net.Http.Json;
using System.Text.Json;

using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization = new("Bearer", Environment.GetEnvironmentVariable("TELVERA_API_KEY"));

var response = await http.GetAsync($"https://api.telvera.io/v1/verify/{verificationId}");
var body = await response.Content.ReadFromJsonAsync<JsonElement>();
if (!response.IsSuccessStatusCode)
    throw new Exception(body.GetProperty("error").GetProperty("code").GetString());

var status = body.GetProperty("status").GetString();
var request = HttpRequest.newBuilder(URI.create("https://api.telvera.io/v1/verify/" + verificationId))
    .header("Authorization", "Bearer " + System.getenv("TELVERA_API_KEY"))
    .build();
var response = HttpClient.newHttpClient().send(request, HttpResponse.BodyHandlers.ofString());
if (response.statusCode() >= 400) throw new RuntimeException(response.body());
req, _ := http.NewRequest("GET", "https://api.telvera.io/v1/verify/"+verificationID, nil)
req.Header.Set("Authorization", "Bearer "+os.Getenv("TELVERA_API_KEY"))

resp, err := http.DefaultClient.Do(req)
if err != nil {
	log.Fatal(err)
}
defer resp.Body.Close()

var v struct {
	Status string `json:"status"`
	Error  struct{ Code string `json:"code"` } `json:"error"`
}
json.NewDecoder(resp.Body).Decode(&v)
if resp.StatusCode >= 400 {
	log.Fatalf("telvera: %d %s", resp.StatusCode, v.Error.Code)
}
uri = URI("https://api.telvera.io/v1/verify/#{verification_id}")
request = Net::HTTP::Get.new(uri, "Authorization" => "Bearer #{ENV.fetch("TELVERA_API_KEY")}")
response = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(request) }
body = JSON.parse(response.body) rescue {}
raise "telvera: #{body.dig("error", "code") || response.code}" unless response.is_a?(Net::HTTPSuccess)
Response · 200 OK
{
  "id": "vrf_0d9a3d2b5ca2439b9af861470d5986bc",
  "status": "verified",
  "phone": "+375290000001",
  "call_to": "+375170000002",
  "expires_at": "2026-10-08T15:39:13Z",
  "verified_at": "2026-10-08T15:38:19Z",
  "metadata": { "user_id": "42" },
  "created_at": "2026-10-08T15:38:13Z"
}

Errors

An error always has the same shape: {"error": {"code", "message"}}. Handle it by code — it never changes; message is an explanation for the developer.

HTTP code What to do
401 unauthorized Check the key in “Settings → API”
402 insufficient_checks Buy a package in the dashboard
403 account_disabled The account is blocked — contact support; no need to change the key
403 test_phone_only Use a live key or your account's number
404 not_found Check the id
405 invalid_request Method not supported at this URL (e.g. DELETE /v1/verify/vrf_…). An unknown URL gives 404
422 invalid_phone Send the number in international format
422 phone_not_supported Numbers of this country aren't supported yet. Don't retry — offer the user another way
422 idempotency_key_reused Use a new Idempotency-Key for each user attempt
422 invalid_request Fix the request body, details in message
429 rate_limited Retry after Retry-After seconds
500 internal_error Retry; if it keeps failing, contact support with X-Request-Id
503 unavailable Retry after Retry-After seconds

Limits per key, independent: POST /v1/verify — 120 per minute and at most 5 new verifications of one number per 10 minutes (a repeat with the same Idempotency-Key doesn't count); GET /v1/verify/{id} — 3000 per minute.

Compatibility. Within v1 we may add response fields, event types and error codes. Don't reject a response because of an unknown field, and handle unknown events and codes as the generic case.

Response · 402 Payment Required
{
  "error": {
    "code": "insufficient_checks",
    "message": "No verifications left. Buy a package in the dashboard."
  }
}

Webhooks

Webhooks

Set the URL on the key in the dashboard (“Settings → API → Edit”). When a verification finishes, we send it a POST with an event — one per verification:

Event When
verification.verified The number is confirmed
verification.expired No call was made. Arrives 35–95 seconds after expires_at, or right away if a new verification is created for the number
  • data is the verification at the time of the event; livemode: false marks a test-key event.
  • Reply 2xx within 5 seconds. Otherwise we retry after 1, 3 and 10 seconds, then stop — you can always get the status with GET /v1/verify/{id}.
  • An event may arrive twice: skip duplicates by id.
  • Every delivery and your server's response are in the dashboard: “Settings → API” → “Delivery log” on the key.
Request body
{
  "id": "evt_5b1f0c7e9a8d4c2f8e6a3b1d0c9f7e2a",
  "type": "verification.verified",
  "livemode": true,
  "created_at": "2026-10-08T15:38:19Z",
  "data": {
    "id": "vrf_0d9a3d2b5ca2439b9af861470d5986bc",
    "status": "verified",
    "phone": "+375290000001",
    "call_to": "+375170000002",
    "expires_at": "2026-10-08T15:39:13Z",
    "verified_at": "2026-10-08T15:38:19Z",
    "metadata": null,
    "created_at": "2026-10-08T15:38:13Z"
  }
}

Webhook signature

Every webhook is signed with the key's secret — whsec_… from “Settings → API”. Verify the signature to make sure the request was sent by Telvera and wasn't modified on the way.

The signature comes in the X-Telvera-Signature header, e.g. t=1791473899,v1=5f2b9c…:

  • t — the time of sending, in unix seconds;
  • v1 — HMAC-SHA256 of the string {t}.{request body}, keyed with your secret, hex-encoded.

How to verify:

  1. Take the request body exactly as received, byte for byte — before parsing the JSON.
  2. Compute HMAC-SHA256 of {t}.{body} with your secret.
  3. Compare the result with v1 using a constant-time comparison.
  4. Reject the request if t differs from the current time by more than 5 minutes — this protects against replaying an intercepted request. Our delivery retries are signed again with a fresh t, so they pass.

After you rotate the secret, we keep signing webhooks with the previous secret too for 24 hours. The header then carries two v1 values: t=…,v1=<signed with new>,v1=<signed with previous>. Accept the request if either one matches — then no webhooks are lost while you update the secret on your server. The code examples already do this.

<?php
function telvera_signature_valid(string $header, string $body, string $secret): bool
{
    $t = null;
    $signatures = [];
    foreach (explode(',', $header) as $part) {
        [$name, $value] = array_pad(explode('=', $part, 2), 2, '');
        if ($name === 't' && ctype_digit($value)) {
            $t = (int) $value;
        } elseif ($name === 'v1') {
            $signatures[] = $value;
        }
    }
    if ($t === null || abs(time() - $t) > 300) {
        return false;
    }
    $expected = hash_hmac('sha256', $t . '.' . $body, $secret);
    foreach ($signatures as $signature) {
        if (hash_equals($expected, $signature)) {
            return true;
        }
    }

    return false;
}

$body = file_get_contents('php://input');
if (! telvera_signature_valid($_SERVER['HTTP_X_TELVERA_SIGNATURE'] ?? '', $body, getenv('TELVERA_WEBHOOK_SECRET'))) {
    http_response_code(400);
    exit;
}
$event = json_decode($body, true);
import crypto from 'node:crypto';

// rawBody — the body as received (express.raw({ type: 'application/json' }))
function signatureValid(header = '', rawBody, secret) {
  const parts = header.split(',').map((part) => part.split('='));
  const t = Number(parts.find(([name]) => name === 't')?.[1]);
  const signatures = parts.filter(([name]) => name === 'v1').map(([, value]) => value);
  if (!Number.isInteger(t) || Math.abs(Date.now() / 1000 - t) > 300) return false;

  const expected = crypto.createHmac('sha256', secret).update(`${t}.${rawBody}`).digest('hex');
  const want = Buffer.from(expected);
  return signatures.some((s) => {
    const got = Buffer.from(s);
    return got.length === want.length && crypto.timingSafeEqual(got, want);
  });
}
import hashlib
import hmac
import time


def signature_valid(header: str, body: bytes, secret: str) -> bool:
    parts = [part.split("=", 1) for part in (header or "").split(",") if "=" in part]
    t = next((value for name, value in parts if name == "t"), "")
    signatures = [value for name, value in parts if name == "v1"]
    if not t.isdigit() or abs(time.time() - int(t)) > 300:
        return False
    expected = hmac.new(secret.encode(), f"{t}.".encode() + body, hashlib.sha256).hexdigest()
    return any(hmac.compare_digest(expected, s) for s in signatures)
using System.Security.Cryptography;
using System.Text;

// body — the request body exactly as received
static bool SignatureValid(string? header, string body, string secret)
{
    long? t = null;
    var signatures = new List<string>();
    foreach (var part in (header ?? "").Split(','))
    {
        var kv = part.Split('=', 2);
        if (kv.Length != 2) continue;
        if (kv[0] == "t" && long.TryParse(kv[1], out var ts)) t = ts;
        else if (kv[0] == "v1") signatures.Add(kv[1]);
    }
    if (t is null || Math.Abs(DateTimeOffset.UtcNow.ToUnixTimeSeconds() - t.Value) > 300) return false;

    var hash = HMACSHA256.HashData(Encoding.UTF8.GetBytes(secret), Encoding.UTF8.GetBytes($"{t}.{body}"));
    var expected = Encoding.ASCII.GetBytes(Convert.ToHexString(hash).ToLowerInvariant());
    return signatures.Any(s => CryptographicOperations.FixedTimeEquals(expected, Encoding.ASCII.GetBytes(s)));
}
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.HexFormat;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

// body — the request body exactly as received
static boolean signatureValid(String header, String body, String secret) throws Exception {
    Long t = null;
    var signatures = new ArrayList<String>();
    for (var part : (header == null ? "" : header).split(",")) {
        var kv = part.split("=", 2);
        if (kv.length != 2) continue;
        if (kv[0].equals("t") && kv[1].matches("\\d{1,12}")) t = Long.parseLong(kv[1]);
        else if (kv[0].equals("v1")) signatures.add(kv[1]);
    }
    if (t == null || Math.abs(System.currentTimeMillis() / 1000 - t) > 300) return false;

    var mac = Mac.getInstance("HmacSHA256");
    mac.init(new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256"));
    var expected = HexFormat.of().formatHex(mac.doFinal((t + "." + body).getBytes(StandardCharsets.UTF_8))).getBytes(StandardCharsets.UTF_8);
    for (var s : signatures) {
        if (MessageDigest.isEqual(expected, s.getBytes(StandardCharsets.UTF_8))) return true;
    }
    return false;
}
// body — the request body exactly as received
func signatureValid(header string, body []byte, secret string) bool {
	var t int64
	var signatures []string
	for _, part := range strings.Split(header, ",") {
		name, value, ok := strings.Cut(part, "=")
		if !ok {
			continue
		}
		switch name {
		case "t":
			t, _ = strconv.ParseInt(value, 10, 64)
		case "v1":
			signatures = append(signatures, value)
		}
	}
	if t == 0 || math.Abs(float64(time.Now().Unix()-t)) > 300 {
		return false
	}

	mac := hmac.New(sha256.New, []byte(secret))
	fmt.Fprintf(mac, "%d.", t)
	mac.Write(body)
	expected := []byte(hex.EncodeToString(mac.Sum(nil)))
	for _, s := range signatures {
		if hmac.Equal(expected, []byte(s)) {
			return true
		}
	}
	return false
}
require "openssl"

# body — the request body exactly as received
def signature_valid?(header, body, secret)
  parts = header.to_s.split(",").filter_map { |part| part.split("=", 2) if part.include?("=") }
  t = parts.find { |name, _| name == "t" }&.last.to_s
  signatures = parts.select { |name, _| name == "v1" }.map(&:last)
  return false unless t.match?(/\A\d{1,12}\z/) && (Time.now.to_i - t.to_i).abs <= 300

  expected = OpenSSL::HMAC.hexdigest("SHA256", secret, "#{t}.#{body}")
  signatures.any? { |s| OpenSSL.secure_compare(expected, s) }
end

Go live

Sandbox

A test key sk_test_… (created in “Settings → API”) works like a live one, but:

  • the call is real, and you can verify only your account's phone number;
  • verifications are not taken from your package;
  • webhooks arrive exactly as in live mode.

In the dashboard's “Sandbox” section you can walk through the whole flow without code and see the real requests and responses.

Support

Open a request in the dashboard: “Support → New request”. Include the X-Request-Id header from the API response — it lets us find the request, the call and the webhook.

TelveraPhone verification by incoming call: requests, responses, webhooks
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