LTE3316-M604 VoLTE

I recently purchased this router but I can't get VoLTE to work, my telephone company (CoopVoce Italy) declares that the service is active. I connected a cordless phone, before dialing the number you hear the tone but then it remains silent and nothing happens. I also don't receive incoming calls, the SIM card is unreachable. Currently there are default settings so VoLTE is enabled, and I noticed that the "phone" light is always on even when I disconnect the phone cable. Can you help me solve the problem?

Thanks