iOS: set 3CX as default dialer app

[Sepultura]

Hi,
in the iOS "Contacts" app it is possible to call phone numbers via 3CX app. But in all other apps (Mail, Safari, ...) clicking a telephone number opens the SIM dialer. How can I use the 3CX app as default instead?

 

[StefanW]

The default dialer cannot be changed in iOS and remains the SIM-Interface.
But instead of tap to dial, press and hold and you get this menu from where you can select 3CX.

 

[Sepultura]

Thanks!