Fork from http://sourceforge.net/projects/jcblock/

	Program: jcblock

	A program to block telemarketing (junk) calls.

	RECENT ACTIVITY:

	(04/2013): Several people have been successful running the
	program on a Raspberry Pi processor using a USB modem. The
	modems that have been used successfully are: US Robotics
	USR805637 and TRENDnet TFM-561U. There is a good writeup on
	the details at:
	http://weeklytechforum.com/2013/03/28/
	                  block-unwanted-calls-with-a-raspberry-pi/

	(12/2013): A minor change was made to the truncate.c file to
	cause data file record truncation after nine months instead of
	after one year. See the 28 December, 2013 entry in the UPDATES
	file for details.

	MODEM SELECTION:

	I have been using the USRobotics model 5686G modem since
	October 20, 2010 and have seen no errors. I have therefore
	decided to recommend using it instead of the Zoom 3048 modem.

	I used the Zoom modem during most of the development work on
	this project. However, late in the testing I discovered that
	occasionally it did not deliver caller ID data between the first
	and second rings. I tried two 3048 units and saw the same result.
	I also upgraded the firmware in one of them with no effect. I
	sent email to Zoom and got no reply.

	If you have a Zoom 3048 modem, definitely use it for evaluation
	of the jcblock program. It will demonstrate all functionality of
	the program and you can start building your blacklist. The symptom
	you will see when the modem fails to deliver caller ID is that a
	call that would normally be blocked by an entry in the blacklist
	will be passed through. To get error free performance, you will
	need to purchase(~$90) a USRobotics 5686G modem.

	If you test the program with other modem brands, please report
	your results (good or bad) using this site's mailing list or by
	contacting me directly from this project's website. I will post
	any useful reports I receive. Thank you...WSH


	PROGRAM DESCRIPTION:

        This program connects to a serial port modem and listens for
        the caller ID string that is sent between the first and second
        rings. It records the string in file callerID.dat. It then
        reads strings from file whitelist.dat and scans them against
        the caller ID string for a match. If it finds a match it accepts
        the call. If a match is not found, it reads strings from file
        blacklist.dat and scans them against the caller ID string for a
        match. If it finds a match to a string in the blacklist, it sends
        an off-hook command (ATH1) to the modem, followed by an on-hook
        command (ATH0). This terminates the junk call.

        The program also updates the date field of a matching whitelist or
        blacklist entry. Entries that are old may then be identified so
        that they may be removed. Note that the program will operate with
        only a blacklist.dat file defined. A whitelist is not required.

        Functions to manage the truncation (removal) of records from the
        blacklist.dat and callerID.dat files are present in file truncate.c.
        Records in the blacklist.dat file that have not been used to
        terminate a call within the last nine months are removed. Records
	in the callerID.dat file that are older than nine months are removed.
	The operations are performed every thirty days. Alternatively,
	entries in the .dat files may be edited manually.

        An additional feature is supported by functions in file tones.c.
        The program will add a record to the blacklist.dat file for the
        current call if the operator presses the star (*, asterick) key on
	a touch tone telephone handset during an allotted time period. The
	program detects the tone via a microphone placed near the modem
	speaker.  Functions in file tones.c detect the presence of tones
	(941 Hz and 1209 Hz) produced by pressing the star (*) key. If an
	answering machine is installed on the same line this feature must be
        restricted to be active only if a call is answered after the third
        ring (the answering machine *must* also be set to answer on the
        fourth or later ring). If an answering machine is not installed
        on the line the star key feature may be made available for calls
        answered after the third or later ring. This option is controlled
        by a conditional compile flag (see the 09/24/10 UPDATES file entry
        for more details). Also see the NOTE: in the file concerning
	an ALSA version conditional compile selection.

        The program requires a serial modem that can deliver caller
        ID and contains a speaker. The recommended unit is the USRobotics
        model 5686G. It will return caller ID if it is sent command:
        AT+VCID=1. Note that the modem is used just to detect a call's
        caller ID and the star key tones; the modem's normal communication
        function is not used. The program may be terminated by sending
        it a SIGINT (Ctrl-C) signal or a SIGKILL signal.

        The program runs on a standard PC (it was written and tested
        on a Dell Dimension B110 running Ubuntu). The features
        supported by functions in files truncate.c and tones.c may be
        removed by disabling conditional compile flags DO_TRUNCATE and
        DO_TONES, respectively, in file jcblock.c. The default serial port
        specifier is: /dev/ttyS0. The program will accept an option to
        select a different port. The syntax of the call is:

                jcblock -p /dev/portID

        The entire program may be compiled with the following command:

        gcc -o jcblock jcblock.c tones.c truncate.c -lasound -ldl -lm

	Linux installations may or may not install the libasound library.
	It is usually installed in /usr/lib. Also, the tones.c file
	includes file asoundlib.h, which is usually located in directory
	/usr/include/alsa. If not installed, they can be by using
	the distribution's package manager. For example, for an Ubuntu
	distribution, the Synaptic Package Manager may be used to
	install alsa-base, to install the library, and alsa-source, to
	install the source files. If /usr/include/alsa is not yet present
	install libasound2-dev. It is also a good idea to install
	alsa-utils in case testing/debugging of the sound interface is
	needed. Here is a full list of the alsa packages I have installed
	on my Ubuntu 10.04 machine (you can show the ones installed on
	your machine by entering 'alsa' in the Synaptic Package Manager's
	Quick Search: window):
	alsa-utils		alsa-base		alsa-source
	libasound2		libasound2-doc		libasound2-dev
	libasound2-plugins	libsdl1.2debian-alsa	linux-sound-base
	gstreamer0.10-alsa	bluez-alsa		libao2

	No doubt some of these are not needed for the jcblock program,
	but if you install all of them, jcblock should run.

	If jcblock is run on a desktop or laptop, a microphone must be
	placed near the modem's speaker and turned on. The volume level
	must then be adjusted so that when the star key is pressed, the
	audio generated causes the program's tone filter thresholds to be
	exceeded.  Mic audio volume may usually be set by a Preferences
	option. For Ubuntu the path is: System|Preferences|Sound. Then make
	sure the proper sound device is selected under Hardware. The mic
	volume may then be set under Input. The setting depends on the
	position of the mic relative to the modem's speaker. The slider is
	quite sensitive. Another way is to use the alsamixer program: choose
	the sound interface (F6) and the Mic slider (arrow keys). Using
	this program you have a numeric setting displayed that can be
	reused. Remember to keep the phone you answer with away from the
	mic, since the mic will respond to the tones received by the
	handset!

        For continuous use, the program should be run on a low-power single
	board computer so that it can be left on all the time.

	More on the whitelist:

	As a result of operational experience it became evident that
	the addition of a whitelist capability would be helpful. The whitelist
	file (whitelist.dat) holds entries containing the telephone numbers
	of calls the user definitely wants to accept. The program checks for
	caller ID matches of these entries first. If a match is found, the
	blacklist check is bypassed and the call is accepted.

	The issue came up when it was discovered that some telemarketers use
	cell phones! For cell phone calls, the 'NAME =' field in the caller ID
	string is usually: 'Cell Phone   XX', where XX is the originating state
	designator (e.g., CA for California). So using the 'NAME =' field as the
	search string in a blacklist entry would cause all cell phone calls
	from the indicated state to be blocked! In addition, the telemarketers
	use several cell phones (probably as employees come and go), so using
	the 'NMBR =' field in the caller ID as the search string does not catch
	new cell phone callers. Adding a whitelist partially solves this
	problem.

	With a whitelist, the user can include entries that contain the cell
	phone numbers of calls they definitely want to receive from a specific
	state (e.g., CA). Then the cell phone 'NAME =' field for the state (e.g.,
	'Cell Phone   CA') can be used as the search string in a blacklist
	entry. With this arrangement all cell phone calls from the state will
	be blocked *except* the ones with numbers present in the whitelist.

	As another example, a person might want to receive calls from just
	certain numbers and no others (an elderly person, for example). In that
	case the records for the numbers of interest would be placed in the
	whitelist and a single record placed in the blacklist that contains a
	field that is present in all caller IDs (e.g., 'NMBR'). Then all
	calls not matched by records in the whitelist would be terminated.

        Country codes:

        The USRobotics (and probably other modems) must be sent a country
        code command if the country of use is other than USA (the default).
	The command syntax is: "AT+GCI=XX\r", where XX is the country code.
        The codes for the USRobotics modem are as follows (check your modem
	'Command Set' documentation for confirmation):

	Austria		0A	Hungary		51	Norway		82
	Belgium		0F	Iceland		52	Poland		8A
	Cyprus		2D	Ireland		57	Portugal	8B
	Czech and
	Slovak Federal	2E	Israel		58	Spain		A0
	Republic
	Denmark		31	Italy		59	Slovakia	FB
	Estonia		F9	Latvia		F8	Slovenia	FC
	Finland		3C	Liechtenstein	68	Sweden		A5
	France		3D	Lituania	F7	Switzerland	A6
	Germany		42	Luxembourg	69	Turkey		AE
	Greece		46	Malta		B4	United Kingdom	B4
				Netherlands	7B

        The command should be sent in the init_modem() function after the modem
	reset command (ATZ) is sent (the location is indicated in the listing).
	Other program changes may be needed to conform to non-USA country telephone
	systems.

        Real-time prototype system:

        The photo shows a prototype jcblock system consisting of a USRobotics
	5686G modem and an eBox-3300 Server-in-a-box (SIB) purchased from EMAC,
	Inc. The SIB contains a Vortex86DX System-on-a-Chip that implements
	most of the functions of a standard x86 PC. The system shown draws about
	6 watts, so the cost of running it 24/7 is minimal. The eBox came with
	a version of Linux installed that did not have the ALSA audio interface.
	Since this application requires a microphone to implement the star (*)
	key feature, I chose to boot a stripped down version of Knoppix from a
	USB memory stick.

	I started with the version included on a DVD with the book:
	"KNOPPIX HACKS, 2nd Edition", O'Reilly, ISBN:978-0-596-51493-8
	and "remastered" it (trimmed its size) using the procedures
	described in hacks #109 and #110 (in addition, I removed all
	documentation and Linux source code, etc.). The result was a
	version that would fit on a CD, for backup. The procedure results
	in a knoppix.iso file which I then used to make USB boot version
	using a procedure I found at:
		http://www.knoppix.net/wiki/USB_Based_FAQ
	Note that if you don't need the star key feature, the program will
	run just fine on the version of Linux that comes with the eBox.
	The Knoppix version has the additional advantage that the gcc
	compiler, libraries and include files needed to compile the program
	are present on the target.

	The knoppix system did not contain an Ethernet module that was
	compatible with the Vortex86DX chip. The needed module is
	r6040.ko. It may be downloaded from a site reached via:
	  http://dir.filewatcher.com/d/Debian/all/net/r6040-source
	The module depends on module mii.ko, which was included with
	Knoppix.

	The photo shows the Knoppix USB stick installed in a front USB
	socket. All application files are contained on the USB stick
	installed in the back. This provides non-volatile storage for
	them, which is needed for the callerID, blacklist and whitelist
	files. The eBox BIOS may be instructed to boot from the USB stick.

	During the process of constructing the knoppix.iso file, as
	described above, I installed a script called startApp in /etc/init.d
`	and link S99startApp to it in /etc/rc2.d to provide for automatic
	startup of jcblock (the grub loader menu.lst file instructs grub to
	boot to level 2). Script startApp mounts the application USB stick
	on /mnt and then runs a setPorts script on it to perform various
	system administration functions not included in the knoppix.iso
	build (some that were forgotten!) before starting the application
	program jcblock. As a result, the entire system starts up and runs
	when the power is turned on without the need for manual operations
	via a terminal and keyboard. Since sshd and ftpd daemons are started,
	all maintenance may be performed via the Ethernet interface. It is
	especially convenient to maintain data files using a Firefox plugin
	called FireFTP. So the system may be maintained through a GUI from
	any computer that can run Firefox (e.g., Windows, Mac, etc.).

	There is the issue of interrupting a write to flash memory by a
	power failure (or turn-off), which could cause damage to the memory.
	The application program is normally blocked in a serial port read
	operation, waiting for a call. The only time writes occur is for a
	short time immediately after a call is received. So, if the unit is
	turned off at other times, no damage will occur to the USB memory.
	On the outside chance that memory is damaged, the application USB
	memory stick may be easily replaced. Since Knoppix loads into a
	RAM disk, no damage can occur to it.

        Wrap-up:

        That about summarizes my experience with this project. The
        system runs continuously at our home and terminates junk calls
        indicated in the blacklist file. After about six months the number
        of junk calls we received decreased to only a few a week as the
        telemarketers removed us from their call lists.

        The easiest way to get started with this project is to just compile
        the program and run it on a standard PC. It works fine that way,
        but you have to leave your PC on all the time to be useful in
        terminating calls. If you do that anyway then you are all set!
        Otherwise you should eventually consider installing it on a dedicated
        low power embedded computer system similar to the one I described
	above. If your PC does not have a serial port, a PCI serial port card
	or USB serial port adapter can be installed at minimal expense.