Just got a missed call from this number, it rang once and then hung up. Googled the number and got here, thanks for the explanations all! won't be ringing it back!

I also got a call on 08 april 2012 at 12.45pm. I didnt answer as I was out but I had no intentions of ringing back luckily enough. I am also on the vodafone network.

Just got a missed call too, it rang once and I googled and got me here. Thankfully I had no plans to ring back. I am a vodafone customer too, very strange indeed.

I got the same missed call today at midday and I did a search and saw the same as you...Scam

Got a response back from the communications regulator Com Reg. Impressed by their swift reply. The more people that notify them the quicker they prioritise blocking the number.
See part message reply from ComReg below;

ComReg has been made aware that mobile consumers have very recently received and are receiving calls from international phone numbers commencing +23 9XXX XXXX.  We understand that these calls may not be genuine and therefore Comreg  is investigating the matter in accordance with its powers under Section 23 (2) of the Universal Service Regulations.
I would advise you not to return the missed calls to phone numbers that begin with these numbers or to answer them, particularly if you do not recognise the number calling , as you may incur significant charges.
In the event that we can block these numbers I will note the particular number calling your father.
Should you have any further queries or require any other assistance you can call our Consumer Line on 01 8049668 or 1890 229668, or email consumerline@comreg.ie.