Are the rules of Tajweed applied to the recitation of the Qur'an also applicable to the Adhan?

There are two types of tajwid rulings: the first is what the Arabic language necessitates in terms of the articulation points of letters and vowelizations indicating grammatical case (harakat al-i'rab). This is called al-lahn al-zahir (the clear mistake), and observing it is obligatory in the adhan, otherwise it becomes invalid, due to the jurists' stipulation of Arabic for the validity of the adhan. The other type is what the language does not necessitate, such as ghunnah (nasalization) and idgham (assimilation). This is called al-lahn al-khafi (the hidden mistake), and it is mustahabb (recommended) to apply it in the adhan but not obligatory, because it beautifies the voice. The jurists have agreed on the recommendation of beautifying the voice in the adhan.