I have installed a cisco spa8000 which is a 8 port SIP ATA device on a MICS 4.1 along with a call pilot 150 3.1. Every thing seems to work fine until you get a call transfered from call pilot to extension, the cust. leaves a message, and when done, hangs up. Employee retrieves message, and at the very end, imediately you get a rapid busy tone for 5 seconds or so, then dead air. Its as if the call pilot does not send "bye" siginal or something. Another major problem, is because C.P. does'nt appear to send disconnect or "bye" siginal, there for it will not release SIP trunk so it hangs until they get "no lines available" go to phone room reboot spa8000, you're all set for awhile!!!!! Repeat!!!! Major not cool.