I have an SV8100 with Analog Trunks. They trunks randomly seem to get stuck. We have Function keys on each phone assigned to the trunks and one or two trunk lights will be on even though there are no active calls. We have had Verizon out and they reported no issues on the lines. We also swapped out the CO card on the system. We called NEC support but their only suggestion was that the calls that went to auto-attendant or voicemail were getting stuck but all of their suggestions didn't pan out. If anyone has any suggestions on what this could be or any tips on how to debug this it would be greatly appreciated.