The correct phone settings are vital for trackZall application. If the settings are not correct the app is not working properly. Typical problem (if settings are not correct) is that app stops working in phone sleep mode.
Allow app to run background - this is asked in startup. Must be answered "Yes/allow"
Location (GPS) use allowed - this is asked in startup. Must be answered "Yes/allow"
Battery saver - This must be disabled. It is by default disabled, but in some cases it is in active state in phone.
Must be then disabled from Settings->Battery->Battery Saver
Whitelisting - Some phones with older Android version (8.0 or older, Doogee etc) require that the app is whitelisted otherwise app stops when phone is in sleep.
Whitelisting settings can be changed in phone settings menu