Is it permissible to pray the 'Isha prayer half an hour before its adhan, based on the fact that its time extends from the redness of the sun at sunset until before the Fajr prayer?

The time for the 'Isha prayer begins when the twilight disappears. It is permissible to pray it as soon as its time enters, whether the call to prayer (adhan) has been made or not. The commonly heard adhan is often delayed past the beginning of the time, as it is recommended to delay the prayer. One must wait for the congregational prayer if they are in a place where it is established.