How to clear Contacts and Call history?
1. Exit Softphone.Pro.

2. Find up the Softphone.Pro settings folder on your computer. The default location is:
if you're using Windows:
C:\Users\[WINDOWS-USER]\AppData\Local\SoftphonePro
, [WINDOWS-USER] is your Windows user name.
if you're using MacOS:
/Users/[USER]/Library/Application Support/SoftphonePro/
, [USER] is your MacOS user name.
3. Remove the file SoftphonePro.db:

4. Open Softphone.Pro. Contacts and Call history are empty.