Hi Laur,
my understanding is that it is normal that I'll be able to dial number in either the +353 8xxxxxxxx format or in the 08xxxxxxxx format. If this is the case that's ok. In either case the call works normally.
It remains a mistery to my as why it worked before but anyway, it is what it is.
In relation to the voice mail, I have no idea if the caller number was private. It could very well be.
Anyway, this clarify my issue and now everything seems to work normally.
Thanks for the support.