This is often done for privacy and security reasons. 

• Privacy Protection: The primary purpose of call masking is to protect the personal phone numbers of the individuals involved. Neither party can see the other's actual phone number, which helps maintain privacy.

• Use in Customer Service and Delivery Services: Call masking is widely used in customer service operations and delivery services. For instance, a ride-sharing service or food delivery app might use call masking to allow drivers and customers to communicate without revealing their actual phone numbers to each other.

• Temporary Virtual Numbers: The process typically involves assigning temporary virtual numbers that redirect calls to the real numbers. These virtual numbers can be set to expire after a certain period, such as after the service is delivered or the transaction is completed.

• Enhanced Security: By masking phone numbers, businesses can reduce the risk of unwanted contact, harassment, or misuse of personal contact information.

• Record Keeping and Monitoring: Call masking can be used alongside call recording and monitoring for quality assurance and dispute resolution, without compromising the privacy of the individual's phone number.

• Regulatory Compliance: In some cases, call masking is used to ensure compliance with data protection and privacy regulations.

Call masking is a useful tool in maintaining privacy, enhancing security, and building trust in business transactions where direct communication is necessary but personal information needs to be protected.