networking - Can I ping the public IP of a 3G dongle?

I want to ping my mobile device. It's a Raspberry Pi which has a 3G dongle and a working 3G connection. I can ping from my device to the outside but not the other way around.

What I've researched so far

1. 
   

   I understand that my provider is giving my dongle an IPv4 address that is behind a many-to-one NAT gateway. Thus I cannot ping my dongle's public IP from the wild internet.

   
   


2. 
   

   To my knowledge my provider (Telekom Germany) still doesn't support IPv6 for mobile connections which may be a potential solution because every device should get its own IP.

   
   


3. 
   

   I know that you can buy SIM cards with static IPv4 addresses. But they are too expensive for my needs

   
   

Am I out of options?