I am sorry for the bad English.
I hope it will be clear that I want to tell.
In those days there were no cellular stations.
Means there could not be a cellular network.
For this reason for phone there is no place to be connected.
Even if the traveler in time has captured with itself cellular, It will have no place to be connected.
And to whom he can call in far 1928?
I am fond 3D of a drawing and video mounting.
Now there are means with which help it is possible to divide a frame into separate layers, as in a photoshop.
So, there is a possibility to add in a frame any object.
Possessing knowledge and having had patience it is possible to make that will blow up brains of many people on a planet...