Chanting is the most important process of the nine processes of bhakti. Certainly, preaching is chanting. Srila Rupa Goswami explains that there is nama-sankirtan, guna-sankirtan, and lilasankirtan. In other words, when we are preaching the glories of the holy name, the glories of Krishna's qualities, and the glories of the Lord's pastimes, that is also chanting.
(Collected Letters to My Disciples, Vol 3, Pg 58 last paragraph )