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+Once you have flashed a FreeCalypso VPM firmware build into your C1xx phone,
+what do you do with it afterward?  In order to play with this voice pseudo-
+modem, you need to connect the headset jack serial cable between your host
+computer and your phone-turned-VPM and run rvinterf.  With rvinterf running on
+the serial or USB-serial port connected to the target, press the red power
+button on the phone - a momentary press is sufficient.  On C11x and C139
+subfamilies you will hear a chirp sound as the firmware boots - this chirp
+(comes unchanged from TI, going back to at least C-Sample, if not earlier) is
+emitted via the buzzer, which is missing on C155/156.  You will see debug trace
+output from the fw in the rvinterf terminal window, and your setup is ready to
+play with using fc-shell.
+
+Every 5 s our VPM firmware sends a keepalive query packet out the serial port
+(it's a FreeCalypso-invented extension to RVTMUX), and rvinterf responds with
+keepalive answer.  If there is no rvinterf, i.e., if you press the power button
+on a VPM-flashed phone with no host computer connected or if you kill rvinterf
+or unplug the serial cable, the firmware will automatically power off in 15 to
+20 s after not receiving keepalive responses.  On buzzer-equipped C11x and C139
+phones you will hear another brief sound (of lower frequency) when the firmware
+executes its poweroff operation.
+
+If you plug in the charging power source (which forces the Calypso+Iota chipset
+to be switched on), the firmware will not power off on its own for as long as
+it is plugged in (the stay-on condition is charging power present OR rvinterf
+present).  If battery charging configuration is present in FFS (and it is
+present in FFS images generated by scripts in the present fc-am-toolkit), the
+battery will also charge - but please see caveats about battery charging at the
+end of C1xx-flashing article.
+
+Bringing up GSM network connection with fc-shell
+================================================
+
+Once you have rvinterf running and communicating with the VPM-flashed C1xx
+phone over the serial cable, you need to open another terminal window and run
+fc-shell.  That second fc-shell terminal window will be the method by which you
+issue AT commands to the GSM MS.
+
+The sequence of AT commands which I (Mother Mychaela) typically use when
+bringing up a test GSM MS is as follows:
+
+AT+CMEE=2	-- enable verbose error responses
+AT+CFUN=1	-- bring up SIM and enable radio functionality
+AT+CREG=2	-- see registration status async responses
+AT+CRC=1	-- extended RING async responses
+AT+CLIP=1	-- show calling number on incoming calls
+AT+CNMI=2,1	-- show indications of incoming SMS
+AT+COPS=0	-- connect to the default operator
+
+Once you are connected to the network, you can dial outgoing voice calls with
+ATDnumber; (semicolon at the end is required - no CSD support in VPM), and you
+can answer incoming calls with ATA.  ATH in an active call will hang up.
+
+If you receive incoming SMS, they will be written into SIM storage (no ME
+storage has been implemented in FreeCalypso yet), and if you did the AT+CNMI=2,1
+step, you will see a +CMTI notification.  You can then read them out with
+fcup-smdump -R (the -R option tells fcup-* utilities to connect via rvinterf),
+and you can decode the retrieved SMS PDUs with sms-pdu-decode.  You can send
+outgoing SMS with fcup-smsend -R - see documentation in FC host tools package.
+
+Once you are done with your GSM play session, do a clean shutdown (IMSI detach
+etc) with AT+CFUN=0, and then power down the VPM phone with fc-shell poweroff.