I am writing on behalf of my bosses who both have smart phones and have experienced what we believe to be tone recognition problems when they call from their smart phones into our office to check their office phone's voicemails. I contacted our phone system service department who said there are issues with several phone systems recognizing Verizon's tones. He also said that he has not heard of this issue with other providers. Is there anyone else out there who has experienced this?
I have some ideas to resolve the concerns you have with the touch tones. First, may I ask what type of devices are been used? Most phones have the option to adjust the touch tone being put out by the phone. The setting is either a long tone or a short tone. In my experience different phone systems react differently to the length of the tone. If you reply with the phone models I will be more than happy to send you the instructions to change the settings and test further. Please let me know if I can assist with any other concerns.