How do I transfer files to ebook reader from phone using either an OTG cable or wifi? I've a rooted Sony reader PRS-T1 (based on Android 2.2) and usually when I need to copy files to it, I connect it to my laptop with a USB cable. However, sometimes I travel without my laptop and have only my phone/tablet.
I tried using an OTG cable, but my phone does not seem to be able to read the reader storage.
Is there a way of transfering files to my reader from my phone without using an external sd-card?
In the past I used to connect to Dropbox in the reader's browser to download files or send the files thorugh gmail, but the browser is very old and this is no longer possible.
Now there are plenty of ways to do this;  perhaps the easiest method given that you have the OTG cable, is just to use a suitable file explorer (preferably MiXplorer which has custom OTG drivers) in case your storage device is formatted in a different file system.

I wrote a guide on MiForum on how to achieve this:  Alternative easy way to mount Pendrive(NTFS FileSystem) via OTG without root its not only limited to ntfs but can also use others like exfat etc.


In your case you just need a USB Flash drive (pendrive) that you can insert on the OTG female port then,
Simply open the app, tap on the three dot menu → More settings → Enable Custom driver for USB OTG (tick the box to enable).
Done, now insert you OTG cable and place the pendrive on the port. The  pendrive will  be recognised without errors, and open the files you need  and copy to and fro the tablet &lt;=&gt; phone as you wish.




Alternatively I have posted a related method here, showing how to do it using wi-fi (which is pretty much related to what you're trying to achieve):


Android to Android file explorer using wifi direct 


Or


File transfer with linux pc through mobile hotspot
Is there a way to access the phone filesystem from computer, wireless?


(In above cases the target tablet will be the pc or "second android device" respectively) 

Hope this helps