fc-simtool and fc-uicc-tool can operate on SIM cards via any of the following 3
access paths:

* The card to be operated on can be inserted into a smart card reader/programmer
  supported by pcsc-lite software stack, such as HID Omnikey 3121 and 6121 card
  readers sold by Sysmocom webshop;

* The card can be inserted into a much simpler serial SIM reader - see the
  Serial-SIM-readers article;

* The card can be sitting inside a Calypso phone or development board - see the
  SIM-in-Calypso-phone article.

In the PC/SC and serial SIM reader use cases, you run fc-simtool or fc-uicc-tool
directly, with the needed options to select the right target.  In the more
special case of operating on SIM cards inside Calypso GSM devices, you have to
use the fc-simint front end described in the SIM-in-Calypso-phone article.

When running fc-simtool or fc-uicc-tool directly to operate on a card inserted
into a dedicated reader/programmer, use the following options to select the
correct target:

-d /dev/ttyXXX

	This option selects the serial SIM reader back end, operating on the
	named serial port.  See the Serial-SIM-readers article for additional
	speed enhancement options.

-p N

	This option selects the pcsc-lite back end, operating on reader number
	N.  If you have only one PC/SC-supported card reader on your system,
	the correct option is -p0.  If you have multiple readers, use
	fc-pcsc-list utility to list them and figure out which number is which.

There is no default: if you run fc-simtool or fc-uicc-tool with neither -d nor
-p, you will get an error.

Each of the two target selection options runs a different back end program
behind the scenes: -d runs fcsim-serial-be, -p runs fc-pcsc-backend.  This
separation allows for subset installations: if someone is only interested in
serial and/or Calypso back ends and does not have libpcsclite installed, they
can omit the pcsc back end, in which case fc-pcsc-backend won't be present and
therefore -p option won't work.  One can similarly omit the serial and Calypso
back ends, although the Mother does not currently know of any practical system
where they would pose compile-time difficulties.