Hello I am new to the forum and although I searched it I couldn't find an answer to my problem. I have a Siemens Hicom 150E Office One installed at our offices(one ISDN outside line and four Optisets ) which worked fine for over two years, lately after a re-programming from the installer it started rebooting every 5-10 min! It actually looks like the power is cut off and comes back, all sets turn off their displays which return after 30-40 seconds . The installer replaced the power supply with another one (refurbished) but the same problem. Then he changed the Hicom with another refurbished one , but still the same. I have disconnected all sets from the Hicom , but no solution, I have also tried disconnecting the carriers digital line (S0) in case there was some junk coming in from the provider but still have problem. Can any one please help me find a solution to this problem?