After talking to o² increasingly dissatisfied Since I'm a member of congstar and congstar is a subsidiary of Telekom and works in the D1 network (which is generally considered to be much more reliable), I'm venturing my first change of provider with number porting. Actually, this should work without any problems, but so far I only have the confirmation from o² that my letter of termination has arrived. The prices at congstar are quite similar to my previous o²o contract, especially the data package with 12.90 Euro for 1 GB (with 7.2 MBit/s, then throttling to GPRS) is attractive. The minute/SMS prices are also pleasantly low at 9 cents, and apart from Internet, a few telephony minutes and a few SMS per month, I don't need any comfort features.
Why I choose congstar and not fyve: in contrast to Vodafone, Telekom equips the base station with EDGE throughout the country, which is not the case at Vodafone, at least not in my opinion. If UMTS does not work, this is definitely an advantage. Let's hope that the porting will run without problems - otherwise, in an emergency fyve to the train for the transition. Of course I will record here how congstar compares to o² in everyday life.
An All-Net-Flat (a comparison of different All-Net-Flatrate tariffs is possible on flat.de) would not have been suitable for me personally, I simply don't make enough calls - no matter which network I use.