Using AirVPN So I Can Use My Cellphone As A Server?

[ableright 0]

So I have a decent amount of knowledge of networking, but I still lack some knowledge at some points.  I'm wondering if it's possible more as a technically of understanding to use a cellphone for say an FTP server on mobile data.  Normally, a computer that was behind a NAT Router on a landline connection you would simply forward port 21 or whatever port the FTP is using to the Local LAN IP 192.x.x.x and bam it works.

 

On cellphones using mobile data for example T-Mobile inbound connections are blocked because the phone is behind a bunch of mobile complex NAT routing etc.  That said, certain applications like Teamviewer for example (which allows remote support on your Android phone) still work much like an inbound connection.  Using Teamviewer as an example, it appears this works because a connection Tunnel/Bridge occurs on Teamviewers servers.

 

In other words let's say a person is working on your mobile phone from their home PC connected as landline connection.  I've done this before, so what is happening is

 

YOUR PC -> Connects To Teamviewers Server <- Cellphone Connects to Teamviewers Server which establishes a connection and Teamviewer is acting as a sort of proxy so to speak.  Couldn't the same thing be done using AirVPN?  I set my cellphone up with an FTP server for example hosting files on the phone, and then it connects to AirVPN's private server (you can use the port forwarding options) and on my PC far away I connect to the public WAN IP on the VPN which then goes to my phone.  

 

Would this work?  Am I understanding how this works correctly or is there an easier way?  I really appreciate the help, and I'm always trying to learn more about networking etc.

[Old Fella 10]

What has this to do with anything VPN? A phone as a server, aye right.