Background / summary: Based on the package that I have, national calls, texts and data traffic is free -- up to some high number that I never reach.
What this deal allows, is to consume parts of your package abroad without additional cost. It does however not change your "country of origin" so to say. So I can make callsto / text some at home and use data for free.
Newer contracts allow precisly this (= completely free calls/texts within all EU three networks) but do so at an additional cost. Data is usually not included.
Since roaming for calls and texts (within the EU) is dirt cheap nowadays anyway, this is not an attractive option :)