Android : Using fixed IP to communicate with AWS in android

Here is the problem we got:

We are working on a device which uses android and has a mobile GPRS modem (Sierra or Gemalto) and using SQS and S3 APIs to communicate with Amazon AWS. When we use the Wifi it works fine, but when we use the GPRS modem we get issues with DNS resolving.

Anybody knows if it is possible to fix the IP for S3 and SQS and communicate with AWS? Making an overview on the API that option didn't seem to be available, so I'll guess I have to start looking through the API code on github.

Any help on this would be greatly apreciated. Thanks!