What is the ruling on a prayer that was established while the Imam's phone was emitting loud music during it, and what is the ruling on a congregant withdrawing from the prayer in this situation, and what is the correct action if this recurs?

The Imam should turn off his phone before the prayer. If he does not, and a call comes in, he should end it with a simple motion that does not invalidate the prayer. Furthermore, the Imam must repent from listening to music. The prayer of both the Imam and the congregants is valid in this case, and what happened is not a justification for interrupting the prayer.