Best to take care using the US collars in France as the frequencies differ. None of the US ones match the 2 reserved in France. There is some discussion on this in an [Only registered and activated users can see links. ] which solves the problem for Nordic users of US Astro 320 by converting localisation of the receiver to use Nordic collars. You could do the same with the ID of a friend's French unit. At present there is no known patch to convert US astro 320 to another localisation as with 220.
The quote below is from the link [Only registered and activated users can see links. ]:
With a warning of that nature i'd be concerned about using any US DCs in FR. Even using FR DCs without a licence is not legal it seems.Use of this equipment in France requires that you obtain a license from theAssociation des Chasseurs Utilisateurs de Fréquences Assignés (ACUFA). You may be subject to sanctions by your local authorities for any unauthorized use.