Thanks for your interest in the Intel® Edison™ Platform.
Could you be so kind to tell us the errors that are generated while attempting to connect the ICOMSAT 1.1 to the Edison? Also, it would be useful to know the code that you are using in order to establish the communication.
We will be waiting for your reply, have a nice day!
I found this Shield Testing guide https://www.intel.com/content/www/us/en/support/boards-and-kits/000020775.html Shield Testing Report for Intel® Galileo Board, Intel® Galileo Gen 2... , where they show how to use the SIM900, maybe it will be useful to you.
Hope you find this information useful, have a nice day!