I've tried everything that came to my mind to resolve my issue.
My scenario is very simple:
1) 15 phones CISCO SPA525G
2) Internal, AsteriskNOW PBX on dedicated LAN server, without NAT, everything on local intranet
What have I did already?
1. Installed clean install AsteriskNOW, turned off firewalls, etc.
2. Configured 15 extensions with passwords (secrets) for my phones
3. Configured phones (similar to this: https://sysadminman.net/blog/2011/using ... eepbx-2714)
And... everything works perfectly fine. I didn't use any external lines, trunk VOIPs, only internal calling between my 15 phones. But I have one problem with ending my calls.
Example: When I call (for example) from phone 102 to phone 104 and I hang up my conversation from phone 102... phone 104 stays connected. Time on display still flies

What I did wrong with configuration? Can anyone help me with this?