Remote host can't match request NOTIFY to call

Ok, I am getting a strange error that I can not seem to find an answer to and I am not even sure what is causing the message as I am not making any calls to the system at the time the error occurs and constantly keeps coming up:

[Apr 10 09:40:47] WARNING[2499]: chan_sip.c:12177 handle_response: Remote host can’t match request NOTIFY to call ‘16aa71cd54fb311a6a393bed697d1320@’. Giving up

Can anyone tell me what might be causing this? I Googled it but got nothing that I could understand. Any help here is greatly appreciated as always :confused:

Can you turn sip debug on and discover what host is causing that NOTIFY?