Pierre,
The PPR requirement at this airfield is clearly published as by telephone call to XXXX
Out of curiosity is the "by phone" but explicitly stated in the AIP entry for your field? Is it also in the flight guides? People use different methods for their briefing, and perhaps the "by phone" bit isn't listed in them all? Just a thought.
Personally, I think people should always call, unless they KNOW that an airfield is happy to accept you on r/t. But that's me, and another debate that we already had
dp