One can apply for information under RTI Orally as well.
Kushal point is correct in the regard that the reduction to writing part of the process will be done by the CPIO/CAPIO.
Section 5 (3) of the RTI reads as
Every Central Public Information Officer or State Public Information Officer, as the case may be, shall deal with requests from persons seeking information and render reasonable assistance to the persons seeking such information.
If a perso is unable to submit is application in writing then CPIO has to reduce his request in writing and process such application.
In out country a large section of population is still illeterate and they cannot be denied the RTI as they cannot write.
I would like to update and add to my earlier answer. Section 6 proviso specifically provides for oral request
Provided that where such request cannot be made in writing, the Central Public Information Officer or State Public Information Officer, as the case may be, shall render all reasonable assistance to the person making the request orally to reduce the same in writing.
CPIO will inform you that they are working on the information and your request for information will be treated as application under RTI only when requiste fees are deposited. Section 6 (1) of RTI is very clear
A person, who desires to obtain any information under this Act, shall make a request in writing or through electronic means in English or Hindi or in the official language of the area in which the application is being made, accompanying such fee as may be prescribed,
A public authority has to discharge a lot of function. The priamry role is to work for public welfare. If the priamary aim becomes only to provide information over telephones then the whole purpose of bringing efficiency will be defeated.
The key word is without the requiste fee a request cannot be treated as Application under RTI.