I used to use OpenSky at a previous job. IMO, it worked and sounded just as good as P25. However, we had one of the few working systems in the country of the handful that are still around.
So, here's how it works and the hang ups that prevent unauthorized radios from monitoring:
- There's very little info to program into RPM. Most is handled at the system level.
- Each radio has it's own IP address. No, you can't clone another radios IP even if you knew one. Your radio has to be sent traffic to receive anything.
- Each radio has a 10 digit ID. When you boot the radio, it logs in with this ID and authenticates to the system. Based on your ID, your appropriate talk group profiles are then downloaded to your radio. The radios can be set to auto log-in or require you to enter this ID upon boot.
Even without encryption, passive monitoring with capable equipment isn't going to happen. Most of the TGs were unencrypted. The encrypted ones, if you had access to them, required a password to be entered upon boot up, no auto log-in.