Si le llamas por teléfono, se pondrá muy contento. It has to do with a a dialectal variation in the Spanish language, called LEÍSMO. This involves using 'le' (indirect object pronoun) instead of 'lo' (direct object pronoun) It happens with male people. Normally, it doesn't refer to animate objects like for example: Veo el perro ("I see the dog") → Le veo. This is not correct at all. But if you say: Veo al chico ("I see the boy") → Le veo. , it is OK in some regions in Spain, although years ago it was wrong. Maybe rules will change. If you say: Veo al chico ("I see the boy") → Lo veo. it's completely correct. So in your example, it would be better using 'lo' because it is a direct object pronoun. 'Leísmo' is commonly used in spoken Spanish. Hardly ever you'll see people say 'lo' in place of the correct one: lo.