ExoNumbers App: Why Should Businesses Have All The Fun?

  • Voice
  • B2C
Automation & 3 more
  • Automation
  • Number Masking
  • Sales calls
  • Virtual Numbers


Have you ever wanted to have a temporary number that’s separate from your primary number without buying a SIM card? The solution is to have an application to be able to buy a virtual number just after a few clicks. Essentially bringing the features of a call center right on your phone. The users will be able to set up various things via the application:

  • Voice Mail 
  • Ringtone
  • Work Hours

Target Audience

Individuals who want to have a temporary number that can be discarded at any time. For example Archimedes has joined a new company in a Sales position. He wants to get a new number so he can separate work and personal calls. He buys a new SIM card and goes about his business.

Instead, Archimedes could have just downloaded the ExoNumbers app and put in his primary number and bought a virtual number that he could distribute to his colleagues and clients. He gets additional benefits like setting work hours. He can just delete the ExoNumber when he decides to leave the company.

Flow Diagrams

OutGoing Call Flow

  • User (Caller) with the ExoNumbers app keys in the destination number (Receiver) and hits the call button. 
  • The app makes an API call to Exotel server.
  • Exotel connects the user and the destination number.

Incoming Call Flow

  • Caller keys in the Exonumber and clicks on call. 
  • Mobile Network will contact Exotel’s backend to get the Receiver’s details based on the ExoNumber.
  • Exotel Initiates call to receiver via Mobile Network.



Different ways this product can be priced:

  • Number Rental: X amount for Y days with Z free calls.
  • Value Added Services: X amount for features like Working Hours, Voice Mail, etc.


  • Buying Virtual Numbers made extremely simple and can be used by any individual. Not limited to businesses anymore.
  • All the infrastructure needed to buy numbers/ make calls are already present. Only need to integrate with the application.
  • Can purchase multiple numbers using one SIM card.
  • Can purchase a number from a different region in the country to gain advantages of having a local number such as increasing engagement.
  • KYC only once with the application while creating the account with Exotel. As opposed to doing KYC every time you buy a SIM card.
  • Features like automated call forwarding would be a lot easier to set up using this app.
  • Can take advantage of all the call features that Exotel provides like recordings, voice analytics, etc all in one place.
  • The default limit for the number of people in a conference call can be extended.
  • A separate address book that can be disposed of once you delete your number. Calls that come from these contacts can be shown in a custom dialler.


  • A smartphone 
  • A valid number with the SIM on that phone at all times

Flow of Application

  • Registering the primary number: When the user first logs into the app, we detect the numbers present in the phone and ask the user to choose a primary phone number. 
  • Authentication: We then verify if the number is present on the device using nOTP. This will need to be done whenever the user opens the app henceforth. If not present, we ask the user to insert the SIM or register a different number that is present on the device.
  • Buying the ExoNumber: Basic details are asked from the user as to where they will be operating the device from and so on. Based on this, we display numbers from which the user can select a number to purchase.
  • Payment: The user can then pay the required amount based on the duration selected.
  • Setting the Flow: By default, the user will be called on their primary number. They can set up a ring tone when calls to their ExoNumber are ringing or set up work hours and greetings for non-work hours in this section.
  • Custom Call Screen


  • Cannot receive SMSs on the virtual number in India because of the restrictions by operators.
  • UPI and other such apps authenticate the phone by sending an SMS from the phone using the same number that is associated with the user’s bank account. The user will not be able to validate the numbers purchased by the app.
  • Need internet for outbound calls

Last modified Date

December 14th, 2023