Real or hoax, you decide:
http://uk.movies.yahoo.com/blog/article/57334/time-traveller-spotted-at-chaplin-premiere.html
Or maybe she’s just scratching her ear/head 
not convinced 
Ha Ha. fascinating 
Pah 1920’s could be an vactube hearing aid of the era.
Though I don’t know how small radios were back then but maybe she listening to Noel Edmunds or Terry Wogan <chuckle>
Or alternative the director is transmitting to radio… ‘Oi you silly mare your spoiling the shot get off the £$%^ set’.
:lol: Looks pretty weird and they apparently say it’s genuine too… Not sure meself.
We associate the position of the hand and talking with something we all do today, which is chat on the mobile phone. However, that’s a bias that makes us want to draw that conclusion when we see someone else going through the apparent motions. The same conclusion would not have been drawn when cell phones were the size of CB radios, and the same conclusion will not be drawn in the future when cell phones are the size of your watch battery. The video is an oddity to be sure, but it is not a person on a cell phone (unless it’s not an authentic video).
'Tis a good’un, innit
Practically - No cells to connect to. Though I have a vague memory of a variation of a ‘mobile’ telephone being invented in the 1920’s where it trailed a ground wire, and used a wired up umbrella as an ariel.
In the 20’s the technology was available. Tho’ not as we know it. Short range wireless voice transmission was available, but the emphasis was on on short.
Gallium arsenide was available used by those in the know as crystals for ‘cats whiskers’ radios - heck, you can even use a bit of coal and a razor blade and a few feet of wire for that for that
All you’d need, in short, is a form of repeater station. A heck of a lot of them.
I guess my point is that the evolution of technology isn’t linear. There’s those technologies that shine and fail because of incompetence or commercial interests. Did Edison invent the lightbulb? No. he simply got his patent in first. Did the Wright Brothers invent Flight. Nah.
Impossible? No. Implausible? You decide…
If you’d like to twiddle, I can post (or y’can google) a simple radio that can be built from household items, and it isn’t that much of a stretch to add a combo hooman/whisker repeater system.
It looks like he is holding a cold compress or similar to his jaw - probably just got a toothache - hand shape hints at a cupping rather than a holding action.