How to make mobile test call?

How to make mobile test call from one mobile phone to another?
Using Sevana QualTest it is easy:

✅Measures quality of mobile calls with regular non-rooted Android phones and iPhones
✅Enables uploads and shares test results
✅Runs both active (with reference audio) and passive tests
✅May be integrated with QualTest Host and correspondent Backend to automate making and receiving mobile test calls
✅Measures quality of mobile calls in the field
Within QualTest one can easily setup these two test scenarios:
🔊 initiate test calls and measure MOS when installed as system application. It is available on rooted phones only. One can view / share / upload test results right from the phone.
🔊 initiate and accept calls without analysis on mobile phone. Rooted phone is NOT required. In this mode application notifies its desktop (Raspberry Pi) counterpart (Qualtest Host, further down QH) about progress of the call. QH handles audio streams via cable adapter and communicates with backend.