Yep, that's very interesting. Looks just like someone on a mobile.
BUT 1. If it is a time traveller who could he/she be talking to in 1928? (unless, of course, they had a channel back to their own time)
2. Why would a man dress up as a woman to do the time travelling?
3. When we see someone with their hand up towards their ear we think of them being on a mobile because that's what we see
very frequently at the present time. I have to admit that many a time I've seen a hand up near someone's ear and thought they were using their mobile only to find that, in fact, they're not.
And, it has to be said that not everything is explainable. Can we really use our present day thinking of hands near ears meaning a mobile is being used? We are using modern day thinking to explain something from 1928.
But, yes, it does look like he/she is using a mobile.