  The F -GAMMA program is a coordinated effort of several observing facilities
to understand the AGN/blazar phenomenon via a multi-frequency monitoring
approach, especially in the era of Fermi-GST. Some 60 prominent sources are
monitored monthly with the Effelsberg 100-m telescope, the IRAM 30-m telescope
and more frequently but in a less uniform fashion at the APEX 12-m telescope,
covering from 2.64 to 345 GHz. The program has been running since January 2007
and here some of its findings are summarized. (a) There are two major
variability patterns that the spectra of sources follow, one
spectral-evolution-dominated and one achromatic. (b) The FSRQs show higher
brightness temperatures indicative of larger Doppler factors at play and (c) a
statistically significant radio-gamma-ray correlation has been found with a
method recently suggested by Pavlidou et al. (in prep.).
