iphone 11 immediately shows 'call failed' when trying to make a call

I am physically in the USA but I use freefr.fr carrier from France

When I landed in France I got a text from freefr providing indications to dial number to France or USA.

Also the text said that coz the discontinuation of 3G in the USA they recommend to use the VoLTE.

What i experienced is the opposite:

VoLTE activated = calls to USA impossible

VoLTE non activated = calls to USA possible

Hope this help

Jean