Baruch Hashem, in Yeshiva Univerisity, there is a phenomenon in that a plethora of young men pile into Room 101, a room directly behind the Main Beis Medrish in Zysman Hall, for afternoon Mincha Services. Unfortunately however, because the room is so small it very quickly gets filled to capacity and forces some to daven outside in the hallway.
A question was once asked to R’ Soloveitchik as to whether or not these people davening outside in the hallway are actually accomplishing Tefilla Bitzibbur.
The question was asked based on the Gemara (Eruvin 92b) which says that a minyan cannot take place in two separate rooms. Nonetheless Tosafos D”H Tisha says that people in the second room may answer during Kadish and Kedusha even if an iron wall is there to separate the two!
Does the Din of Tefilla Bitzibbur go according to the laws of answering kedusha? Or does it go according to being mitztareif with a minyan?
After thinking for a few minutes the Rav answered that the Din is in accordance with the opinion that it is like answering kedusha. Therefore the Rav paskined that anyone who davens outside in the adjoining hallway can still participate in Tefilla Bitzibbur and does not have to trouble themselves in trying to force into the cramped room. (Also in the Aruch Hashulchan O”C S’55 S’K 23)