I monitored many centers from the east cost to the west coast
(Boston, NY, Chicago, Portland, Denver,...)
What suprprised me is that controllers did not only use the facility ID
when aircraft cheked in on a new frequency ("XY center rodger" instead
of the commonly used "radar contact" or "identified" in Europe) but
in almost every transmission. At least that was my impression.
Many thanks for the answers guys
