Apple decided to add a prompt dialog when a call is being initiated from an app in their iOS update 10.3.1, this will also affect iCarMode’s dialer behavior and all similar dialers out there.
I am sorry for the inconvenience.

“Phone

Available for: iPhone 5 and later, iPad 4th generation and later, iPod touch 6th generation and later

Impact: A third party app can initiate a phone call without user interaction

Description: An issue existed in iOS allowing for calls without prompting. This issue was addressed by prompting a user to confirm call initiation.

CVE-2017-2484”

https://support.apple.com/en-us/HT207617