Cannot call from contact entity on Mobile

The functionality on clicking the horn of a telephone is not working.
However if you swipe and on the detail level of a contact and you click on the number then a phonecall is initiated, when you close the call you see that the system is in creation mode of phone call entity
then you can decide to save or not.

However clicking on the horn was possible before?

See also MS documentation which explains how to perform this.

https://www.microsoft.com/en-us/dynamics/crm-customer-center/email-and-call-customers-in-dynamics-365-for-phones-and-tablets.aspx 

The user has an apple phone, i have an adroid : i checked and have also the same result.

How can we solve this.