Taxis queue outside S- and U-Bahn stops and can also be hailed from the street at the same rate. This is Germany; you won’t get ripped off. Calling a taxi is an option as well; mention to the operator if you want to pay by credit card, as not all taxis have card-reading equipment.
Taxi-Zentrale, tel. 06 92 30 01
Zentral 33, tel. 069 23 00 23
Echofunk, tel. 069 79 20 20.