Q. I will be arriving erev pesach to the hotel around 11.00 am and will miss the siyum which is earlier, can I ask a friend attending the siyum to contact me at the airport or my car during the siyum so I can hear it by phone. Does that count as being there?
A. On question 198 on this forum namely: If you learned together (a tractate of the Talmud) with a group but now are on vacation somewhere else, can you join (the siyum fleishig banquet during the nine days) via telephone? We answered; Horav Shlomo Miller's Shlit"a ruled that if you learned the whole tractate you can join the siyum via telephone. However, if you did not study, you cannot just dial – a- siyum. Similar opinions are to be found in other Poiskim (Mekadesh Yisroel, Pesach 256, et al.).
Likewise if one learned the Masechta to be finished and is on his way to the siyum he could join via telephone the siyum.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit"a