Who Should Give Adhan?
Question

Who is qualified to give the call to prayer? In other words, who shoulders the responsibility for this task? Is there any particular type of person who should do that?
Praise be to Allah.Who should give the Adhan?
It is not stipulated that the Adhan (call to prayer) should be given by any particular person, so if a Muslim man gives the call to prayer, the communal obligation to give the call is waived from the people of that locality, because the Prophet (blessings and peace of Allah be upon him) said: “Let one of you give the call to prayer, and let the oldest of you lead you in prayer.” (Narrated by Al-Bukhari, 628, and Muslim, 674)
Conditions of the Mu'adhdhin
The scholars have mentioned some conditions that should be met by the Mu’adhdhin, and some desirable qualities that should be paid attention to.

One of those conditions, without which the Adhan is not valid, is that the Mu’adhdhin should be a male Muslim of sound mind.

Ibn Qudamah (may Allah have mercy on him) said: “The Adhan is not valid unless it is given by a male Muslim of sound mind. As for the disbeliever or one who is insane, it is not valid if either of them gives it, because they are not people who are obliged to do acts of worship. Additionally, the Adhan given by a woman does not count, because she is not one of those for whom it is prescribed to give the Adhan. … And we do not know of any difference of scholarly opinion concerning that." (Al-Mughni, 1/249)
Desirable qualities of the Mu'adhdhin

Regarding the desirable qualities, it is desirable that the Mu’adhdhin should have a beautiful voice, and he should be trustworthy, of good character, knowledgeable about the times of prayer, and an adult.

Ibn Qudamah (may Allah have mercy on him) said: “It is recommended that the Mu’adhdhin should be of good character, trustworthy and an adult, because he is in a position of trust and people refer to him to know the times of prayer and when to start and break the fast, so there is the possibility that he may deceive them if he does not have these characteristics. Moreover, he gives the call to prayer from a high place, so there is the possibility that he may look into private spaces.” (Al-Mughni, 1/249)
It says in Al-Mawsu`ah Al-Fiqhiyyah, 2/368:

“One of the desirable characteristics in the Mu’adhdhin is that he should be of good character, because he is entrusted with the times for prayer, and he is trusted not to look into private spaces.

 The Adhan is valid if it is given by an evildoer, although that is disliked. … It is desirable that he should have a beautiful voice, because the Prophet (blessings and peace of Allah be upon him) said to ‘Abdullah ibn Zayd: “Get up and go with Bilal, and teach him what you saw (in your dream), for he has a more melodious voice than you,” and he is more able to make his voice reach the people.… It is desirable that he should be knowledgeable about the times of prayer, so that he can watch out for it and give the call when the time for the prayer begins. The one who is sighted is better than one who is blind, because the one who is blind does not know when the time for prayer begins.”
However, it should be noted here that if the mosque has a regular Mu’adhdhin , no one should compete with him in giving the Adhan, or transgress against him by giving the Adhan instead of him, except with his permission.
For more details, please see this category: Call to Prayer.
And Allah knows best.