Hazrat Mahdi (pbuh) will preach the religion of Islam from his home by means of broadcasting systems such as television, radio

Imam Muhammad al-Baqir ordained as follows:
WHEN OUR QAIM ASCENDS... THEY WILL HEAR HIM WHEN HE DESIRES TO SPEAK TO THEM AND THEY WILL SEE HIM, EVEN WHEN HE IS IN HIS OWN RESIDENCE.
(Yevmul Halas, page 269) (Hazrat Prophet and the Ahlul Bayt Golestan, Bir Demet Gül [A Bunch of Roses], Author: Ustad Sayyid Kemal Fakih Imani, Translation: Kadri Çelik, Kevser Publishing House 2005, Page 97)