Microsoft has not resolved the problem with TAPI voice modems in Windows 10 1903 as of yet, but a detailed working solution has been published on our site getfaxing.com. We cannot post a link here to due restrictions to our account, but will include quick solution listed below: here is the solution: Using regedit, locate the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32 In the Drivers32 key, locate all keys listed with “wave#”. For example, “wave“, “wave1” , “wave2” etc. Determine the last “wave#” key value that exists. If you only see “wave” listed here, then create a new string value named “wave2” with the string data “serwvdrv.dll“. If you have multiple keys that exist such as “wave“, “wave1“, “wave2“, then add the the next available new string value. For example, “wave3” with the string data “serwvdrv.dll“ If you are using a 64-bit Windows 10 version 1903, you must repeat step above also using the following key: HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Drivers32 Restart Windows 10.