UMTS network – Port forwarding issue

Hello everybody. Here is my problem:
The UMTS network that i use does not allow port forwarding at all. All users use the same ip address and this one happens cause the provider uses a proxy server probably.

So, how what can i do about it? I run many servers on the pc and i need to maintain access for remote users.

Any help would be usefull. Thanks a lot for reading this.