In the company I’m working we have our own iOS\Android\WP apps which allow our employees to share a certain type of files to each other. This app works through our server but recently we encountered a situation when some of our employees need to reach to each other, they’re even in the same building, but can’t due to a restricted connection to the internet outside of the country. Installing a server in this country is out of the question so now we’re looking for an alternative solution.

Is there any way to make two mobile devices with the app to connect directly to each other in order to exchange information? Using e-mail or any other common communication is out of the question since files sent from one app to another had to be processed and displayed in a very specific way (it’s complex technical specifications) plus policy of our company strictly prohibits usage of a 3rd party servers to exchange information.

The problem we’re facing is that since both devices are simply using a local mobile ISP it’s impossible to establish a direct TCP connection because both devices don’t have an external IP address which could be used to reach this device. So as far as we can tell trying to connect 2 devices directly over the internet is a lost cause. Are we correct in this assumption? Maybe we’re overlooking some possibility to achieve our goal? 

I will appreciate any ideas.