What are Number Masking Calls?

Number Masking and why this is important

In this guide, you will be acquainted with what is Number Masking calls.

Imagine this, you picked up a call on your mobile, and it is your taxi driver. He wants to confirm your address as he is lost. All is good at the end and you get to your destination. What is the problem then? From that day onwards, he is texting good morning to you everyday.

Privacy is widely considered to be crucial in contemporary society. In today's interconnected world, where digital technologies play a significant role in various aspects of our lives, the importance of privacy has become even more pronounced.

What is Number Masking?

Number masking, also known as phone number anonymization or virtual phone numbers, is a technique used to protect the privacy of individuals when communicating via phone or messaging services. Here are some key reasons why number masking is important:

  • Privacy Protection: Number masking helps individuals keep their personal phone numbers private when interacting with others, especially in situations where they may not want to share their direct contact information. This is particularly relevant in online transactions, classified ads, or when using ride-sharing services.
  • Security in Business Transactions: Businesses often use number masking to facilitate communication between customers and service providers while ensuring the privacy and security of both parties. For example, in the context of online marketplaces or service platforms, number masking can prevent misuse of personal phone numbers.
  • Preventing Harassment and Spam: Number masking can be an effective measure to prevent harassment and spam. By using virtual phone numbers, individuals can avoid giving out their real phone numbers and reduce the risk of receiving unwanted calls or messages.
  • Enhanced User Trust: Implementing number masking in communication services can contribute to building trust among users. When people know that their contact information is shielded, they may be more inclined to participate in various online activities without the fear of privacy invasion.
  • Security in Dating Apps and Social Platforms: Number masking is often employed in dating apps and social networking platforms to facilitate communication between users while safeguarding their personal contact details. This helps create a safer online environment.
  • Temporary Communication Needs: In situations where temporary or short-term communication is required, such as for online transactions, job postings, or event planning, number masking allows users to interact without exposing their primary contact information.
  • Reducing Fraud Risks: Number masking can help mitigate the risk of fraud by limiting the exposure of personal phone numbers. This is especially relevant in scenarios where individuals are dealing with unknown parties, such as in online sales or peer-to-peer transactions.
  • Compliance with Regulations: In some regions, there are regulations and privacy laws that require businesses to take measures to protect individuals' personal information. Number masking can be a tool to assist in compliance with these regulations, ensuring that sensitive information is handled responsibly.
  • Workplace Communication: In professional settings, number masking can be used for business-related communications. It allows employees to interact with clients or customers without disclosing their personal phone numbers, maintaining a boundary between work and personal life.
  • Control over Communication: Number masking gives individuals greater control over who can contact them and when. Users can deactivate or change virtual numbers as needed, providing a level of flexibility and control that is not always possible with a permanent phone number.

How does Number Masking work at Unifonic?

In a nutshell, businesses will need to creating pairings of two parties, to be within a Number Masking Session. This ensures that party A will not know the true mobile number of party B, and vice versa.

Businesses will interact with Unifonic via the Number Masking API to create and manage the number masking sessions. In order to use Number Masking APIs, customers need to first create a Number Masking Application, and link it to a DID number. Read this guide to find out more.

This DID number then becomes the Masking Number.

Party A and Party B will then call this Masking Number on their mobile phones to get to each other. This call will be a normal PSTN call on both ends.

Below is the example of the actual scenario:

Call Scenario

Party A will call the masking number on their mobile phone, generating an inbound leg at Unifonic.

Unifonic will then use the masking number to make another call to Party B, generating an outbound leg at Unifonic.

Both of these legs are then combined, so that party A and B can converse.


Number Masking APIs

To understand how to make use of Number Masking APIs, refer to this guide.

Technical Architecture



The business first need to use the Number Masking API to create a session, be returned a masking number, and reveal that masking number to both parties, as they will be dialing and receiving calls to/from this masking number.

Unifonic utilizes two components to enable the number masking solution:

  • Programmable Layer
    The programmable layer is basically an orchestration of calls based on active number masking pairings/sessions. Based on the pre-defined sessions that are saved in the database, Unifonic is able to know what to do when we receive a call from a party.
    • In case this party is indeed mapped with another party in a number masking session, Unifonic will simply create another call to the other party and adjoin the two calls. (certain configurations can be made on the application to play an audio file before adjoining both calls)
    • In case this party is not mapped with another party in any number masking session, Unifonic will simply hang up the call. (certain configurations can be made on the application to play an audio file before hanging up on the call)
  • SIP Trunks
    Unifonic utilizes its direct SIP connectivity to the local vendor/operator in order to provision a Masking Number to the business, and make use of this number to receive and send calls.
    • In case your business wishes to bring your own connectivity instead of using Unifonic's connectivity, check out this guide.