  We present a new catalogue of ALMA observations of 3,364 bright, compact
radio sources, mostly blazars, used as calibrators. These sources were observed
between May 2011 and July 2018, for a total of 47,115 pointings in different
bands and epochs. We have exploited the ALMA data to validate the photometry
given in the new Planck Multi-frequency Catalogue of Non-thermal sources
(PCNT), for which an external validation was not possible so far. We have also
assessed the positional accuracy of Planck catalogues and the PCNT completeness
limits, finding them to be consistent with those of the Second Planck Catalogue
of Compact Sources. The ALMA continuum spectra have allowed us to extrapolate
the observed radio source counts at 100 GHz to the effective frequencies of
ALMA bands 4, 6, 7, 8 and 9 (145, 233, 285, 467 and 673 GHz, respectively),
where direct measurements are scanty, especially at the 3 highest frequencies.
The results agree with the predictions of the Tucci et al. model C2Ex, while
the model C2Co is disfavoured.
