Have you tried reaching out to your Unication Dealer? As a dealer myself, I'm always there to help my customers program in any system they need help with.
Just make sure your trying to program in a P25 system. The G5 won't work with any other trunk system.
If you are having problems with Out of Range, try removing the Site and RFSID and enter the wildcard FFF for both. Also - make sure your WACN and ID settings are correct for the system you are trying to monitor. And start small - just put your local site in there for now and then expand out with the other sites in the network, but only if you need them.
Feel free to contact me if you need any other help programming your G5. It's a great little pager!