How To Verify Phone Number for Free Using WhatsApp

If you have a product or business that maintains user information like phone numbers, verifying the validity or ownership of the phone number could become important, as the phone number can be used as an authentication method or targeted marketing channel. The typical phone verification procedure is by generating a code or OTP in our application, sending that OTP to the user's phone, and then the user should insert the OTP in our application for verification. The OTP can be sent to the users through services like SMS or WhatsApp that require a valid phone number. For internet-based communication, WhatsApp has become the de facto standard for sending the OTP. WhatsApp requires its users to have a valid phone number during account creation, and it already has a huge number of users, approximately 3 billion in 2025.

Using that common procedure, WhatsApp will charge us for each OTP sent. The cost depends on the country of the target phone number. For Indonesia, typically the cost is around IDR 350 per OTP sent, depending on the service provider. There is another method that can clear out the cost. It is based on the WhatsApp pricing scheme itself that will not charge us for receiving messages from our users or directly replying to those messages within a 24-hour window. After 24 hours, we can only send messages using pre-approved templates, which may come with a cost. User-initiated conversations do not count against your messaging limits, allowing you to reply freely.

Understanding this WhatsApp policy, we can set different flows for verifying user phone numbers.

First, register a business and a WhatsApp phone number in Meta Business. Remember that the service we use is not the WhatsApp Business App on our mobile phone, but it is the WhatsApp cloud service that requires us to deploy a webhook to receive messages from WhatsApp.
In our application, we can drive our user to send a special formatted message to our WhatsApp Cloud phone number. We can generate a link filled with text that contains a special message that our application will understand. The link format is typically like this: http://wa.me/YOUR_PHONE?text=SPECIAL_MESSAGE
When our webhook receives the users' messages, the webhook should be able to differentiate between normal messages and messages for phone verification based on the format we have specified. We can extract the user phone number information along with the special code contained in the message.

To implement this phone verification flow, there is a free service we can utilise. It is available on bilangin.com. This method still requires us to maintain our own WhatsApp Cloud phone number in Meta Business, but without the need for a custom webhook deployment. These are the steps we should follow to use this free service.

First, after registering a WhatsApp account for your business, generate an access token by creating a service account in Meta Business, and give the account the required permissions to access WhatsApp messages.

Second, store your WhatsApp information in bilangin.com, including the access token.

Third, after the creation, keep the webhook URL and the verification token shown in the bilangin.com dashboard.

Fourth, create an application in Facebook Developer, enable the WhatsApp integration, and configure the webhook. Set the webhook to subscribe to WhatsApp message events.

Fifth, create a phone verification entry in bilangin.com. This entry will define how Bilangin will process your users' messages and pass the extracted information to your application for phone verification. Keep the handler ID for the later step.

Double-curly braces are used to extract your application-defined variables included in the user text message. Single-curly braces are for system variables such as message metadata. Currently, it is only for the "{PHONE}" variable to retrieve users' phone numbers in received WhatsApp messages.

Sixth, prepare your application to handle phone verification requests from your users. It includes generating a model and a message formatter to provide a message that will be sent by your user. Bilangin accepts the following text message format.

###PV###<HANDLER_ID> | <KEY1>: <VAL1> | <KEY2>: <VAL2> | Some texts

The message should start with "###PV###", followed by the handler ID. You can add multiple key-value pairs that need to be extracted for the verification process in your application, such as special code, request ID, etc. Each block is separated by the pipe symbol, "|".

Lastly, prepare your endpoint to handle the payload sent by Bilangin defined in the fifth step. The following diagram shows a general overview of the whole process.

Comments

Rangkaian Sensor Infrared dengan Photo Dioda

Keunggulan photodioda dibandingkan LDR adalah photodioda lebih tidak rentan terhadap noise karena hanya menerima sinar infrared, sedangkan LDR menerima seluruh cahaya yang ada termasuk infrared. Rangkaian yang akan kita gunakan adalah seperti gambar di bawah ini. Pada saat intensitas Infrared yang diterima Photodiode besar maka tahanan Photodiode menjadi kecil, sedangkan jika intensitas Infrared yang diterima Photodiode kecil maka tahanan yang dimiliki photodiode besar. Jika tahanan photodiode kecil maka tegangan V- akan kecil . Misal tahanan photodiode mengecil menjadi 10kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 10 / (10+10) x Vcc V- = (1/2) x 5 Volt V- = 2.5 Volt Sedangkan jika tahanan photodiode besar maka tegangan V- akan besar (mendekati nilai Vcc). Misal tahanan photodiode menjadi 150kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 150 / (1...

Deploying a Web Server on UpCloud using Terraform Modules

In my earlier post , I shared an example of deploying UpCloud infrastructure using Terraform from scratch. In this post, I want to share how to deploy the infrastructure using available Terraform modules to speed up the set-up process, especially for common use cases like preparing a web server. For instance, our need is to deploy a website with some conditions as follows. The website can be accessed through HTTPS. If the request is HTTP, it will be redirected to HTTPS. There are 2 domains, web1.yourdomain.com and web2.yourdomain.com . But, users should be redirected to "web2" if they are visiting "web1". There are 4 main modules that we need to set up the environment. Private network. It allows the load balancer to connect with the server and pass the traffic. Server. It is used to host the website. Load balancer. It includes backend and frontend configuration. Dynamic certificate. It is requ...

Configuring Swap Memory on Ubuntu Using Ansible

If we maintain a Linux machine with a low memory capacity while we are required to run an application with high memory consumption, enabling swap memory is an option. Ansible can be utilized as a helper tool to automate the creation of swap memory. A swap file can be allocated in the available storage of the machine. The swap file then can be assigned as a swap memory. Firstly, we should prepare the inventory file. The following snippet is an example, you must provide your own configuration. [server] 192.168.1.2 [server:vars] ansible_user=root ansible_ssh_private_key_file=~/.ssh/id_rsa Secondly, we need to prepare the task file that contains not only the tasks but also some variables and connection information. For instance, we set /swapfile as the name of our swap file. We also set the swap memory size to 2GB and the swappiness level to 60. - hosts: server become: true vars: swap_vars: size: 2G swappiness: 60 For simplicity, we only check the...

What's Good About Strapi, a Headless CMS

Recently, I've been revisiting Strapi as a solution for building backend systems. I still think this headless CMS can be quite useful in certain cases, especially for faster prototyping or creating common websites like company profiles or e-commerce platforms . It might even have the potential to handle more complex systems. With the release of version 5, I'm curious to know what updates it brings. Strapi has launched a new documentation page, and it already feels like an improvement in navigation and content structure compared to the previous version. That said, there's still room for improvement, particularly when it comes to use cases and best practices for working with Strapi. In my opinion, Strapi stands out with some compelling features that could catch developers' attention. I believe three key aspects of Strapi offer notable advantages. First, the content-type builder feature lets us design the data structure of an entity or database model , including ...

Installing VSCode Server Manually on Ubuntu

I've ever gotten stuck on updating the VSCode server on my remote server because of an unstable connection between my remote server and visualstudio.com that host the updated server source codes. The download and update process failed over and over so I couldn't remotely access my remote files through VSCode. The solution is by downloading the server source codes through a host with a stable connection which in my case I downloaded from a cloud VPS server. Then I transfer the downloaded source codes as a compressed file to my remote server through SCP. Once the file had been on my remote sever, I extracted them and align the configuration. The more detailed steps are as follows. First, we should get the commit ID of our current VSCode application by clicking on the About option on the Help menu. The commit ID is a hexadecimal number like 92da9481c0904c6adfe372c12da3b7748d74bdcb . Then we can download the compressed server source codes as a single file from the host. ...

Armin or Commander Erwin

In the moment of conflict in the scout team, who will be revived?

LUKI NOTES

Search This Blog