Ok so a better search and found this is common on and to get telco to fix the issue as with the other system I had installed. I should have learned from the XBlue system I had done, I think its sinking in.

After blowing the dust off the old system. I put it up this week and installed a VoIP card. Have been using VoIP services for over a year and did not like it. Went back to my old system and something just is not right. System works fine get incoming calls no problem but here is the issue.
Dial tones are on Time Warner and can call in to system ring to phones and answer with no problem, hang up and the line opens up. After setting the voicemail group up and sending the calls to it they get answered and transferred to the extension. If you answer the call and hang up its fine but if you let it go to voicemail and hang up it does not release the ports. I have played with the disconnect timers with no change. I have tested it with a analog telephone and can hang up no problem. I think it is the POTS lines from TM but 100% sure of this. As I do not have a standard POTS line to test my theory with.
Anyone have an idea of this issue?
Only thing I know is when I packed it away it worked fine and has not been touched since, I did add the FP4 to it and the VoIP card. I am thinking that I must not be getting good disconnect from TM. I have had this problem with XBlue system and had telco make some changes and it works fine. The site had a fax line to put in the system to verify this issue.

"It works on our end so it must be fine."