All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
The most correct opinion of the scholars is that it dislikeable for a person who does not have ablution to make the call for the prayer. However, if he makes the call for the prayer without being in a state of purity then that is sufficient, whether the person only requires ablution, or needs a ritual bath. The evidence that it is disliked is that once Al-Muhaajir Ibn Qunfuth passed by the Prophet while the latter was urinating, and he greeted him with Salaam. The Prophet did not respond to him until he performed ablution and then apologized to him and told him that he did not want to mention Allaah (by responding to the Salaam) in a state of impurity. [Abu Daawood].
Nonetheless, other scholars are of the view that it is permissible for a person who does not have ablution or is in a state of major impurity [requires a ritual bath] to make the call for the prayer. While others consider that the call for the prayer is not valid except in a state of purity. Still other scholars however, distinguished between the first call for the prayer and the second call (Iqaama) which means that the prayer is ready to start. So they conditioned the state of purity for the second call for the prayer. Some other scholars even distinguished between not having ablution and being in a state of major impurity.
To conclude, the most correct opinion is that which is stated at the beginning of this Fatwa.
Allaah knows best.