According to The Twentieth Century Encyclopedia of Catholicism regarding the sacrament of penance:
"Absolution can only be given to one who is morally present, and this means, according to the teaching of St. Alphonsus Ligouri, that he must not be more than twenty paces distant from the confessor. In the case of extreme necessity (much as that of a man who is falling from a roof at a considerable distance away) this moral presence may be interpreted broadly. This question of distance is one that sometimes arises in the ordinary life of an average parish were it is not uncommon for a penitent to leave the confessional before the priest has had time to give him absolution. On such occasions it is often possible to recall a penitent to the confessional, or failing this, to absolve him, as he moves away from the confessional, while he is still within the prescribed distance. It is not essential that the confessor should be able to see or hear him."
"Pope Clement VIII by a decree of June 20th, 1602, condemned the proposition that a confession might be made in writing or through an intermediary in the absence of the penitent, and that absolution might be given in such circumstances (i.e. with the penitent still absent). This ruling does not prevent a penitent from sending a written statement to the confessor in advance, and from later accusing himself in a general way in the presence of the confessor, who already in a general way in the presence of the confessor, who already knows the details from the letter. This is an altogether different situation from that condemned by Clement VIII. It does not involve a confession made by a penitent who is absent, or absolution given to him while he is still absent."
Except in case of extreme necessity it is forbidden to give absolution by telephone or by means of a speaking tube, but it is not clear that absolution given in this way would be certainly invalid. Everything depends here upon what it meant by being orally present, and it has been plausibly argued that, if the penitent and his confessor can be said to converse audibly, they may fulfil the4 condition of being present one to the other. "
"Is it necessary to add that a certain popular novelist, whose works have been translated into English, is in error if he really believe that a priest can transmit sacramental absolution by telegram"?
Volume 51
Section 5: The Life of Faith
"Absolution can only be given to one who is morally present, and this means, according to the teaching of St. Alphonsus Ligouri, that he must not be more than twenty paces distant from the confessor. In the case of extreme necessity (much as that of a man who is falling from a roof at a considerable distance away) this moral presence may be interpreted broadly. This question of distance is one that sometimes arises in the ordinary life of an average parish were it is not uncommon for a penitent to leave the confessional before the priest has had time to give him absolution. On such occasions it is often possible to recall a penitent to the confessional, or failing this, to absolve him, as he moves away from the confessional, while he is still within the prescribed distance. It is not essential that the confessor should be able to see or hear him."
"Pope Clement VIII by a decree of June 20th, 1602, condemned the proposition that a confession might be made in writing or through an intermediary in the absence of the penitent, and that absolution might be given in such circumstances (i.e. with the penitent still absent). This ruling does not prevent a penitent from sending a written statement to the confessor in advance, and from later accusing himself in a general way in the presence of the confessor, who already in a general way in the presence of the confessor, who already knows the details from the letter. This is an altogether different situation from that condemned by Clement VIII. It does not involve a confession made by a penitent who is absent, or absolution given to him while he is still absent."
Except in case of extreme necessity it is forbidden to give absolution by telephone or by means of a speaking tube, but it is not clear that absolution given in this way would be certainly invalid. Everything depends here upon what it meant by being orally present, and it has been plausibly argued that, if the penitent and his confessor can be said to converse audibly, they may fulfil the4 condition of being present one to the other. "
"Is it necessary to add that a certain popular novelist, whose works have been translated into English, is in error if he really believe that a priest can transmit sacramental absolution by telegram"?
Volume 51
Section 5: The Life of Faith
Comment