We are having an issue with one way audio. Our system worked perfectly fine for a week, then we closed for the holidays, came back and the phones had one way audio when calling in. If we call our 3cx system we dont hear it ring and dont hear the virtual attendant, but if I enter an extension it calls it and I can hear audio on the 3cx side but not on the external phone. If our VOIP phone initiates the call and calls out audio works both ways. We recently replaced our modem because of jitter and the new modem worked perfectly for the week mentioned, but now we have this issue. I noticed in the 3cx logs that there were several errors stating on RTP packets received. Could the modem be the culprit ? Any suggestions?