I got a used Polycom 550 and I'm trying to get it setup. I'm not getting a 0x4020 error on the phone. I'm running the Debian version of 3CX (v15). I seen the steps to setup a Polycom 550 and to copy the support files, but the instructions are for a Windows server based 3CX. http://www.3cx.com/sip-phones/polycom-soundpoint-450-550-560-650-670/ Any help? Thanks!