I am running 3CX with a Grandstream GXW4108 gateway and GXP2000 phones. The issue I am having is that when I make a call to someone outside of the network over the PSTN lines, if they hang up first, my phone never disconnects the line and eventually I get the operator message saying "If you would like to make a call, please hang up and try again." I have contacted Grandstream tech support and they are questioning the SIP signalling coming from the 3CX system. I have SYSLOG captures from the gateway and phone, and the red flag I am seeing is that when the PSTN side hangs up, the GXP2000 shows that it receives a SIP message and then has a parse error. Here are the lines from the syslog server: 2007-07-19 11:55:05 User.Debug 192.168.3.37 GS_LOG: [00:0B:82:0D:F0:4E][FF71] SIPReceive(4, Account1): 2007-07-19 11:55:05 User.Info 192.168.3.37 GS_LOG: [00:0B:82:0D:F0:4E][FF71] Received SIP message: parse error 2007-07-19 11:55:24 User.Info 192.168.3.37 GS_LOG: [00:0B:82:0D:F0:4E][FF71] Send SIP message: BYE To 192.168.3.207:5060, sip_handle: 0x004B809A The last line is the BYE message it gets when I hang up the GXP2000 after receiving the operator message. Any thoughts or help?