cisco 2811 cme/cue. with fxo ports for pstn access. call to any of the fxo from anywhere work fine except from the siemens call box which simply dials the fxo number based on pushing a button on the call box. Sometimes one way audio, sometimes works, sometimes cuts out. I tried echo cancel 64 and input 14 output 4. Works better if human voice answers but get one way audio using auto attendant. Very strange.
