If one attends a Siyum virtually, whether by phone, Skype, or some other means of mass communication, can one partake of the Se'udath Mitzvah (relevant to allow eating meat during the 9 Days for Ashkenazim and to exempt a first-born from fasting on 'Erev Pesah)?
If one cannot partake in the siyum in person, some permit him to listen to the siyum via telephone. This should only be relied upon in extraordinary situations. (Horav Shlomo Zalman Aurbach zt"l quoted in Yoma Tova L'rabanan page 70 footnote 16, see Modanei Shlomo (Moadim) page)
R' Shlomo Zalman Aurebach (quoted by Gershon Gold) permitted partaking in a siyum over the telephone in extenuating circumstances.
Although R' Shlomo Zalman (Minchas Shlomo 1:9) took a very strong view against using microphones/telephones to discharge obligations (such as Havdala or Tefilla), he apparently held that a siyum is different.
There is a dispute among the Poskim which component of being present at a Siyum permits a bechor to eat - hearing the siyum, or partaking in the seudas mitzvah (see Minchas Yitzchok 9:45 and Teshuvos VeHanhagos 1:300 quoting the Steipler). One obvious difference is if one arrives after the siyum took place, but still partakes of the seuda.
Seemingly, R' SZ Aurebach held that there is no need to actually hear the Siyum (because he strongly believed that hearing something over a telephone does not halachically constitute hearing), but just to partake of the Seudas Mitzvah.
It is very possible that R' SZ only said this regarding Taanis Bechorim, but not in regards to eating meat during the first 9 Days of Av.