Incoming Call wont drop when caller failed to disconnect

I received a call around 3 pm today and the caller failed to disconnect. I picked up my phone a little while ago to make a call, dialed the number and received nothing. I then tried the voicemail number 123 and it connected me to the call in progress where I could hear my original caller talking in the background, tried this repeatedly and finally cloned a second line but my original line is still held up. I also disconnected and reconnected the voipo device repeatedly to no avail. This is a definite flaw as I don't want to be held accountable for incoming minutes that are not mine. Is there no way to drop an incoming call if the caller doesn't hang up? Opened Ticket JAY-442077. Caller calling from a Verizon Wireless phone. Caller found his phone off the hook and hung up at 5:46 pm and my Voipo phone now ok. - Attempted the exact scenario using my Verizon wireless phone and the minute I hung up the Voipo line, the Verizon phone disconnected so must have been a fluke but definitely and odd one.