I just set it up for the first time yesterday. I haven't change default settings. I tried another cordless phone but, unfortunately, it did not work either. Finlay, I tried test call (804) 222-1111. This test recognized correctly DTMF tones and repeated them back when I pressed 1,2,3.. However, the GV still does not recognize the numbers when I try to respond to its voice menu. It looks to me that the DTFM tones are not strong or clear enough for GV system to recognize them.