SendDTMF method was added to the Phone library. This library requires .Net CF 2.0 and WM5.0 or WM6.0 device (Smartphone or Pocket PC Phone Edition). 1. Extract the zip file and copy the files to: C:\Program Files\Anywhere Software\Basic4ppcDesktop\Libraries 2. Phone.dll should be used on the device and PhoneDesktop.dll should be used on the desktop.