When I arrived here last year I needed an internet connection quickly. There were no avaliable ADSL lines here in Kavos so I fell for the "Free Internet" con.
Since then, I've researched this subject extensively and they are certainly NOT free. The phone number you have to use begins with 801 which OTE will tell you costs 3.64 cents per minute plus FPA (VAT) at 19% = 4.33 cents or €2.60 (euro) per hour.
I still don't have an ADSL line so I'm still restricted to dial up but now I use what's known as an EPAK number. These begin with 89624 or 89625 and cost 41.9 cents per HOUR between 08:00 and 22:00 or 20.9 cents per HOUR between 22:00 and 08:00 including FPA.
To get an EPAK number I buy an internet card from a kiosk or Multirama etc. Various companies issue the cards, the one I use is called NETKEY from Forthnet and is available for €5 for 20 hours use, €10 for 50 hours use or €20 for 2 months unlimited use.
You need to do the sums depending on how much you use the internet to decide which is cheapest for you.
If you used it for 20 hours with a 801 number it would cost you €52
20 hours with an EPAK number would cost:
Daytime..... €8.38 + €5 (for the card) = €13.38
Nightime.... €4.18 + €5 = € 9.18