SMS spend drops when you stop paying for messages that can't arrive and move expected messages to cheaper channels the recipient already uses. A check before sending finds invalid and duplicate numbers for free. It also finds lines that can't take SMS, and it tells you which opted-in contacts can be reached on a messenger instead.
Where does SMS money get wasted?
Most wasted spend falls into four groups:
- Badly formatted or impossible numbers. Typos, missing country codes and numbers that can't exist. The API parses each one and marks it
invalid_number, at no charge. - Duplicates. The same person entered twice in different formats, for example
07700 900001and+447700900001. After E.164 normalization they are the same number, and the repeat is markedduplicate, also free. - Lines that don't take SMS. Fixed lines and some special number types. The carrier lookup reports
line_type, and for US and Canadian numbers there is a bulk carrier lookup. - Messages that could go elsewhere. Some opted-in contacts prefer a messenger such as WhatsApp, Viber or RCS, where the per-message price may be lower than your SMS rate.
The first two are free to find. The last two cost a check each, so they're worth it where your SMS rates are high.
How does the workflow look?
For list cleaning, use bulk jobs:
- Call
POST /v1/jobs/estimatewith the list and the checks you plan to run. It's free and shows how many rows are valid, invalid, duplicate, already cached, unsupported or suppressed, plus the maximum cost. - Create the job with
POST /v1/jobsand pass the estimate's amount asmax_cost. - Wait with
GET /v1/jobs/{id}?wait=30, or subscribe to thejob.completedwebhook. - Download the results as CSV or NDJSON (
GET /v1/jobs/{id}/download?format=csv). The file keeps your original row order and adds one column per check. - Remove invalid rows, set fixed lines to voice or e-mail, and route contacts to the channels they opted into.
For messages sent one at a time, such as order updates, a real-time lookup before each send does the same job.
What should you do with each result?
| Result | Suggested action |
|---|---|
number_status: invalid_number | Remove the number or ask the customer to correct it |
number_status: duplicate | Keep one row per person |
line_type: fixed_line | Don't send SMS; use voice or e-mail |
line_type: mobile | Send SMS as usual |
Messenger registered: true and the contact opted in to it | Consider sending on that channel |
Messenger registered: false | Keep SMS for this contact |
Any check unknown | Keep your current routing. Unknown results are free, so you lose nothing but the check |
How much does it cost?
Bulk checks cost less per check than real-time lookups, and invalid, duplicate and suppressed rows are never charged. You're not charged for inconclusive results (unknown, unsupported country, timeout, invalid, duplicate). See pricing for current rates.
To work out whether it pays off, multiply the checks you plan to run by the bulk price. Then compare that with the SMS spend you would avoid: messages to invalid and duplicate numbers, messages to fixed lines, and messages you can move to a cheaper channel. Checks of the same number inside the freshness window are served free from your account's cache, so running an updated list again doesn't bill the same numbers twice.
Example request
First, a free estimate. The list below holds two valid test numbers, one duplicate and one invalid entry:
curl https://api.mobilevalidate.com/v1/jobs/estimate \
-H "Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" \
-H "Content-Type: application/json" \
-d '{"numbers":["+447700900001","+447700900002","+447700900002","12345"],"checks":["whatsapp","viber"]}'// npm install mobilevalidate · Node.js 20+ · save as check.mjs and run: node check.mjs
import { MobileValidate } from "mobilevalidate";
// Omit apiKey to read MOBILEVALIDATE_API_KEY from the environment.
const mv = new MobileValidate({ apiKey: "mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" });
const { data, error } = await mv.jobs.estimate({
numbers: ["+447700900001", "+447700900002", "+447700900002", "12345"],
checks: ["whatsapp", "viber"],
});
if (error) console.error(error.code, error.message);
else console.dir(data, { depth: null });// Node.js 18+, Deno, Bun or the browser console (ES module: save as .mjs or use "type": "module").
const res = await fetch("https://api.mobilevalidate.com/v1/jobs/estimate", {
method: "POST",
headers: {
Authorization: "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym",
"Content-Type": "application/json",
},
body: JSON.stringify({
numbers: [
"+447700900001",
"+447700900002",
"+447700900002",
"12345",
],
checks: ["whatsapp", "viber"],
}),
});
console.log(res.status, res.headers.get("x-request-id"));
console.dir(await res.json(), { depth: null });# pip install mobilevalidate-sdk
from mobilevalidate import MobileValidate
# Omit api_key to read MOBILEVALIDATE_API_KEY from the environment.
mv = MobileValidate(api_key="mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
result = mv.jobs.estimate(
numbers=["+447700900001", "+447700900002", "+447700900002", "12345"],
checks=["whatsapp", "viber"],
)
print(result)<?php
$ch = curl_init('https://api.mobilevalidate.com/v1/jobs/estimate');
curl_setopt_array($ch, [
CURLOPT_POST => true,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPHEADER => [
'Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym',
'Content-Type: application/json',
],
CURLOPT_POSTFIELDS => json_encode([
'numbers' => [
'+447700900001',
'+447700900002',
'+447700900002',
'12345',
],
'checks' => ['whatsapp', 'viber'],
]),
]);
$response = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_RESPONSE_CODE), PHP_EOL, $response, PHP_EOL;package main
import (
"fmt"
"io"
"net/http"
"strings"
)
func main() {
body := strings.NewReader(`{"numbers":["+447700900001","+447700900002","+447700900002","12345"],"checks":["whatsapp","viber"]}`)
req, err := http.NewRequest("POST", "https://api.mobilevalidate.com/v1/jobs/estimate", body)
if err != nil {
panic(err)
}
req.Header.Set("Authorization", "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
req.Header.Set("Content-Type", "application/json")
res, err := http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer res.Body.Close()
out, _ := io.ReadAll(res.Body)
fmt.Println(res.Status, string(out))
}require "net/http"
require "json"
uri = URI("https://api.mobilevalidate.com/v1/jobs/estimate")
req = Net::HTTP::Post.new(uri)
req["Authorization"] = "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym"
req["Content-Type"] = "application/json"
req.body = JSON.generate({
"numbers" => [
"+447700900001",
"+447700900002",
"+447700900002",
"12345"
],
"checks" => ["whatsapp", "viber"]
})
res = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(req) }
puts res.code, res.bodyRuns as pasted with the public sandbox key, which answers the test values only. In the SDKs, omit the key to use MOBILEVALIDATE_API_KEY.
Response (test mode):
{
"object": "estimate",
"total": 4,
"valid": 2,
"invalid": 1,
"duplicate": 1,
"cached": 0,
"unsupported": 0,
"suppressed": 0,
"checks": ["whatsapp.registered", "viber.registered"],
"checks_total": 8,
"billable_max": 0,
"max_cost": {"amount": "0", "currency": "USD"}
}Test keys are never charged, so billable_max and max_cost are zero here. With a live key they show the most the job could cost. Only the two valid numbers would be checked. The same checks for one-off sends run in real time:
curl https://api.mobilevalidate.com/v1/lookup \
-H "Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" \
-H "Content-Type: application/json" \
-d '{"numbers":["+447700900001","+447700900002"],"checks":["whatsapp","viber"]}'// npm install mobilevalidate · Node.js 20+ · save as check.mjs and run: node check.mjs
import { MobileValidate } from "mobilevalidate";
// Omit apiKey to read MOBILEVALIDATE_API_KEY from the environment.
const mv = new MobileValidate({ apiKey: "mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" });
const { data, error } = await mv.lookup({
numbers: ["+447700900001", "+447700900002"],
checks: ["whatsapp", "viber"],
});
if (error) console.error(error.code, error.message);
else console.dir(data.results, { depth: null });// Node.js 18+, Deno, Bun or the browser console (ES module: save as .mjs or use "type": "module").
const res = await fetch("https://api.mobilevalidate.com/v1/lookup", {
method: "POST",
headers: {
Authorization: "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym",
"Content-Type": "application/json",
},
body: JSON.stringify({
numbers: ["+447700900001", "+447700900002"],
checks: ["whatsapp", "viber"],
}),
});
console.log(res.status, res.headers.get("x-request-id"));
console.dir(await res.json(), { depth: null });# pip install mobilevalidate-sdk
from mobilevalidate import MobileValidate
# Omit api_key to read MOBILEVALIDATE_API_KEY from the environment.
mv = MobileValidate(api_key="mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
result = mv.lookup(
numbers=["+447700900001", "+447700900002"],
checks=["whatsapp", "viber"],
)
print(result)<?php
$ch = curl_init('https://api.mobilevalidate.com/v1/lookup');
curl_setopt_array($ch, [
CURLOPT_POST => true,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPHEADER => [
'Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym',
'Content-Type: application/json',
],
CURLOPT_POSTFIELDS => json_encode([
'numbers' => ['+447700900001', '+447700900002'],
'checks' => ['whatsapp', 'viber'],
]),
]);
$response = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_RESPONSE_CODE), PHP_EOL, $response, PHP_EOL;package main
import (
"fmt"
"io"
"net/http"
"strings"
)
func main() {
body := strings.NewReader(`{"numbers":["+447700900001","+447700900002"],"checks":["whatsapp","viber"]}`)
req, err := http.NewRequest("POST", "https://api.mobilevalidate.com/v1/lookup", body)
if err != nil {
panic(err)
}
req.Header.Set("Authorization", "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
req.Header.Set("Content-Type", "application/json")
res, err := http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer res.Body.Close()
out, _ := io.ReadAll(res.Body)
fmt.Println(res.Status, string(out))
}require "net/http"
require "json"
uri = URI("https://api.mobilevalidate.com/v1/lookup")
req = Net::HTTP::Post.new(uri)
req["Authorization"] = "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym"
req["Content-Type"] = "application/json"
req.body = JSON.generate({
"numbers" => ["+447700900001", "+447700900002"],
"checks" => ["whatsapp", "viber"]
})
res = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(req) }
puts res.code, res.bodyRuns as pasted with the public sandbox key, which answers the test values only. In the SDKs, omit the key to use MOBILEVALIDATE_API_KEY.
Response (excerpt, test mode: the checks of the second item, a number with no accounts):
{
"whatsapp.registered": {
"service": "whatsapp.registered", "status": "completed", "registered": false, "attributes": null,
"confidence": "high", "confidence_score": 0.99, "checked_at": "2026-09-25T14:28:31.050Z",
"cached": false, "age_seconds": 0, "billed": false, "reason": null, "poll_after_ms": null
},
"viber.registered": {
"service": "viber.registered", "status": "completed", "registered": false, "attributes": null,
"confidence": "high", "confidence_score": 0.99, "checked_at": "2026-09-25T14:28:31.050Z",
"cached": false, "age_seconds": 0, "billed": false, "reason": null, "poll_after_ms": null
}
}What limits and rules apply?
A job takes up to 50,000 numbers and e-mails and up to 20 checks. The total of rows × checks can't exceed 100,000 per job. Requests that look like sequential number ranges or generated e-mail lists are rejected. Each account also has a daily cap on numbers, which GET /v1/limits reports.
Clean only lists you collected lawfully, such as your own customers and contacts who opted in. Channel checks help you reach people who want your messages more cheaply. They are not a way to find new people to message, and our acceptable use policy forbids unsolicited bulk messaging.
Frequently asked questions
How much can I save?
It depends on your list quality and your SMS rates. Run a free estimate on a sample to see how many numbers are invalid or duplicate, then compare the price of a bulk check with your SMS price for the destinations you send to.
Is the estimate really free?
Yes. POST /v1/jobs/estimate counts valid, invalid, duplicate, cached, unsupported and suppressed rows and returns the maximum cost without checking anything or charging you.
Can I move marketing messages to WhatsApp because a number has an account?
Only for people who opted in to hear from you on that channel. Having an account is not consent, and messaging platforms require opt-in for business messages.
Should I use real-time or bulk checks for list cleaning?
Bulk jobs. They take up to 50,000 numbers and e-mails per job, run every active service including bulk-only ones, and cost less per check than real-time lookups.
Do duplicate or invalid numbers cost anything?
No. They are flagged per row with number_status invalid_number or duplicate and are never checked or charged.
Related
- ServiceCarrier and line type lookup for any phone number
- ServiceUS and Canada carrier lookup for phone numbers
- ServiceCheck if a phone number is registered on WhatsApp
- ServiceCheck if a phone number is registered on Viber
- ServiceCheck if a phone number can receive RCS messages
- Use caseChannel selection for consented messaging
Guides on this topic
All articlesDeliverability
How to clean a phone number list in bulk, step by step
A step-by-step way to clean a phone list with the MobileValidate jobs API: free estimate, dedupe, invalid rows, capped cost, CSV download and data purge.
7 min read
Fraud prevention
IRSF: international revenue share fraud, explained
How international revenue share fraud turns your calls and texts into someone else's income, how it differs from SMS pumping, and how to cap your exposure.
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Deliverability
RCS capability check: what it tells senders before they send
What an RCS capability check tells you before sending, iPhone support, RCS vs SMS fallback, what RBM is, and a decision table with bulk API examples.
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