I presume the "cutting" problem is about insufficient shielding of the module antenna connection and possibly less than perfect ground connection. It won't happen with a module that has an onboard coaxial connector.
In this case, the suggested shielded box is probably the only promising way to isolate the module input from good GSM network at your place. If you try something on your own, you'll need good bypass capacitors and/or filters for module power supply and data lines, too.
I also expect that the antenna port of a telit GT683 terminal is sufficiently shielded for your purposes.