After checking with my provider it seems that the method described here (incl. my comments) uses HSCSD and not GPRS. The difference between them is that with GPRS you are charged per data volume and with HSCSD per time connected.

1) This is GPRS, not HSCSD.
2) It does not matter which of the two option under the header 'Access the internet using your phone's data connection' is chosen (titled 'Dial a specific access number...' and 'Use a direct, higher speed connection ... (GPRS)').

My mobile phone provider's staff seem to be highly incompetent, of the about eight people I talked to during my five visits to their flagline store only one was able to understand the basic concepts of this hint. Their reaction ranged from 'We don't no shit, and we are proud of it' over complete misinformation 'GPRS does not work on the Razr in our network' and 'You are probably using HSCSD' to astonished reactions 'You downloaded these outdated modem parameters from our website?'

However, their network seems to be the state-the-art, by mid-year 20% (40% at the end of the year) of the population is going to be covered by HSDPA (High Speed Downlink Packet Access), allowing for 1.8 Mbps internet access over the mobile phone network.