fc-simtool can operate on SIM cards that sit inside a Calypso phone or FC
development board, as opposed to the more classic case of operating on a SIM
inserted into a dedicated card reading/programming station.  However, this
special Calypso mode of operation works in an unusual way: instead of invoking
fc-simtool (or fc-uicc-tool) directly, you have to run a front end program
called fc-simint.  fc-simint loads and runs simagent on the Calypso device the
same way how fc-loadtool loads and runs loadagent, then it passes the open file
descriptor to fc-simtool via the special internal-use-only -C option.

fc-simint and its simagent back end reside in the FreeCalypso host tools
package (along with fc-loadtool and other Calypso tools), not in FC SIM tools.
fc-simint and simagent have been added to FC host tools as of fc-host-tools-r15
release.  The latest official release of FC host tools can always be found here:

ftp://ftp.freecalypso.org/pub/GSM/FreeCalypso/fc-host-tools-latest.tar.bz2

Please refer to doc/SIM-manipulation article in the FC host tools package
(r15 or later) for further usage instructions.