Answer by Rabbi Chaim Hillel Raskin – Rov in Kfar Chabad Beis, Israel:
There is a biblical prohibition to call one’s father or mother by their name, even if they are not present, for doing so displays a lack of respect.
Whether prefacing the parent’s name with a title of respect such as “Reb” or “Father” would make it permissible when they aren’t present (as it is regarding one’s teacher’s name) is a question in halacha. Some poskim permit it, (though some limit it to when one is speaking to an individual, but not in a public speech).
Others distinguish between the two and explain that by a teacher since one may have multiple teachers, saying “my teacher” wouldn’t suffice. By parents, however, one could just say “my father” or “my mother,” thus there is no allowance to use their name with a title. In practice, one should be stringent.
If one is asked for his father’s or mother’s name (i.e. by an aliya or mi shebeirach), one may verbalize their name, since it would obviously not help to answer “my father.” Preferably one should preface a title, especially if it is announced publicly. Yet, whenever their actual name isn’t necessary, for example when a person calls up his own father for a kibud, he should say “my father my teacher” and not mention their name.
What if a person has a friend with the same name as his parent? Is he allowed to call them by name in front of his parent?
Some say that it may never be mentioned in the parent’s presence, and it may be only be mentioned in the parent’s absence if it’s a common name. With an uncommon name, one should use a slight variation when referring to the friend, or mention their family name as well. In cases that is clearly evident that he is not referring to his parent (e.g. in a story or dvar Torah), it is permitted.
Others hold that the prohibition only applies when it is both a unique name and it is in the parent’s presence. The prevalent custom follows this opinion, particularly since today hearers won’t suspect that he is referring to his parent.
Published in the Weekly Farbrengen, a newsletter by Merkaz Anash. See sources