Hi
This might be a late solution for your issue and you might already have a fix yourself but in case if it's not, the following solution might help you.
If you're using CRM 2013, the latest rollup UR4 for SP1 includes the new OrgDBOrgSetting to prevent from marking the phone call complete automatically.
You can use the OrgDBOrgSettings Tool from Microsoft to add/edit the settings. You need to download the latest tool (CRM2013-Tools-KB3122951-ENU-amd64.exe) from the UR4 download page.
Update Rollup 4 for Microsoft Dynamics CRM 2013 Service Pack 1 (KB 3122951)
To use the tool, refer to
OrgDBOrgSettings tool for Microsoft Dynamics CRM.
Take note that this page has not been revised for UR4 and added the two new setting names. They're as follow.
- DisableNavTour
- MakeSocialPanePhoneCallCompleted
I am not sure for other CRM versions so you might want to try and see if this apply.
Hope this help.
Cheers