[ldarby]

> It would not make sense to train a model for every advertiser and then upload that to the phone.

I was assuming that's what they were doing. Maybe you could combine both ways, with really imprecise models, so the phone captures and upload only words that above average chance of matching (so not that much data), and have heavy servers do the rest?

Yes I don't work in this field, but you shouldn't assume that just because you don't know how something can be achieved, then no one else has figured it out either (especially where they're motivated to keep it secret).