Translation of indirect article (a, an) into Russian pronouns

Sometimes English indirect article may be translated into Russian pronoun in the meaning of one.But it is a trouble to translate an article into Russian.There are no such categories in this language.In most cases such pronoup appears before a surname.is a Mrs.Это некая миссис Эрлинн.A Mr. Fox called you.Вам звонил некий мистер Фокс.A Smith asked for you.Какой-то Смит спрашивал тебя.Так в конце концов, разве же он не Гриффитс?