Fax number mandatory for income tax efiling registration?

Today i tried to register for a partnership firm on Incometaxefiling site.. and saw as error with regard to FAX NUMBER.. there was a "*" mark, making it mandatory... Wondering what is going on... Many people dont use Cell phone, thought it is mandatory, as if Govt is giving free cell phone to every person :) And many people do not have Email id.. coz they dont know computer nor they use Internet.. still is it mandatory.. Still both can be obtained at no cost or low cost... but Now if FAX Number is also mandatory.. how to deal with it? (Repeat the Telephone Number itself, to avoid the error and file return) what will be the next mandatory detail...