A call from a mobile application using CallBack, and not by substituting a number into the dialer

Good afternoon, when linking a box with a PBX, by default, we call back from the desktop as follows: Click on the phone number = CallBack to the internal number of the employee, then the employee picks up the phone, and then the client is dialed. This is quite normal operation of the system. When dialing a client from a mobile application, our number is simply substituted into the mobile phone dialer, this is not convenient if you would like to call back from a centralized number. At the same time, from the desktop using any PBX, you can implement CallBack to a mobile employee.