Indeed, but they place of advertising the tefillin would vary. For large battim, you would do Chabad media. For Chassidish, maybe Kol Ha'olam. For modern Orthodox or not-so-yeshivish, social media. For Lakewood Yeshivish, a sign in BMG.
But that is probably not the focus of this thread, so I'll refrain from hijacking it.
It is okay to hijack ;-)
My point is: If the battim are XXL, you need to contact Chabad everywhere, so you skip Antartica.
Regular sized + double paired and/or checking the shape of the letter Shin on the Shel Rosh, we are looking for a chosid (not chabad), so we still need to look pretty much everywhere.
Practically speaking, if someone is looking for his Tfillin, he should follow the last posts of this topic.