[Freeswitch-users] Fax (RX): Missing name/header variable in socket!?

[Dennis]

but with all fax-machines i know, one can enter a header, like a
company name, and this header will be seen on the incoming fax in the
head, most of the time at the side of the fax-number. if i receive a
fax with my fax-machine, i can often even see these header-information
in the display of my fax-machine, while receiving the fax.

where do those information come from and how can i access them?