Hungary already has a separate telecommunication tax paid after every minute of phone calls and every sent message (SMS or MMS). The telco providers (T-Mobile, Telenor and Vodafon are the three major players here) were supposed to pay this from their own profit without making the customers pay for it, but that is of course not how the market works. The current proposed internet tax would be based on the amount of data transfer.
In some countries there are already telecommunications taxes/duties that would also be 'internet tax'
I guess the phrasing can be a big deal.