Linux call blocker, blocks unwanted calls from your home phone
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Blocks unwanted calls from your home phone, such as telemarketing, junk, spam, scam, etc.

The call blocker acts like a normal phone. No additional telephone switchboard (like FreePBX or Asterisk) is needed. When a telemarketer is calling, the call blocker picks up the phone and automatically hangs up after a few seconds. Like this the call is blocked. It's designed to run on devices with small footprints, such as a Raspberry Pi. When the call blocker is not running (e.g. hardware broke) your home phone is still working by design. Also it has the ability to check against online and offline phone spam lists.


  • supports VoIP systems and analog modems
  • automatically blocks unwanted incoming calls
  • logging of all incoming calls, including caller name lookups
  • import your addressbook as whitelist or blacklist
  • different kind of blocking modes
    • logging only
    • number blocking using blacklists only
    • number blocking using blacklists and avoid blocking, if number is in whitelist
    • number has to be in whitelist, all other numbers are blocked
  • different kind of ways to verify incoming calls
    • user maintained offline blacklist
    • extern maintained offline blacklists (downloaded from the Internet and stored offline)
    • support of online spam check sites, for spam verification
    • detect anonymous and invalid numbers
    • support range of numbers matching whole areas/regions
  • different kind of ways to get caller name of incoming calls
    • using whitelists and blacklists as offline lookup for caller name
    • support of online lookup sites, to find out who is calling
  • online request caching
  • nice web interface


Supported (tested) server host systems

  • Raspberry Pi
    • raspbian/jessie (use v0.10.x release)
    • raspbian/stretch (use master branch)
  • Debian GNU/Linux
    • jessie (use v0.10.x release)
    • stretch (use master branch)

Supported (tested) VoIP systems

  • Fritzbox 7390

Supported (tested) analog modems

  • USRobotics 5637

Install daemon on Linux

sudo apt-get install git make automake g++ libpjproject-dev libjson-c-dev libphonenumber-dev
sudo apt-get install python3 python3-bs4 python3-ldif3 python3-vobject
git clone
cd callblocker
automake --add-missing --foreign
./configure --prefix=/usr --sysconfdir=/etc
make all
sudo make install
cd /etc/callblocker
sudo mv tpl_settings.json settings.json
sudo vi settings.json
sudo systemctl start callblockerd.service

Install web interface on Linux

The installation of the web interface is optional, the callblock daemon works perfectly without it. The web interface allows to view the caller log, change settings and diagnose problems.

Debian packages are required:

sudo apt-get install lighttpd python3-systemd python3-pip apt-transport-https

nodejs is required, install like described here:

curl -sL | sudo -E bash -
sudo apt-get install -y nodejs

Fetch (within the checkout directory) and install vendor files:

cd callblocker/usr/var/www/callblocker/js
npm install
sudo cp -r node_modules/ /usr/var/www/callblocker/js/vendor

Prepare lighttpd, for additional information see here:

sudo pip3 install flipflop
sudo usermod -a -G systemd-journal www-data
sudo vi /etc/lighttpd/lighttpd.conf
  • in the upper part you find the section 'server.modules='. Please add the module "mod_fastcgi" to it.
  • make server.document-root point to "/usr/var/www/callblocker"
  • at the end of this file add this code:
   fastcgi.server              = (
        ".py" => (
                "callblocker-fcgi" => (
                        "bin-path" => "/usr/var/www/callblocker/python-fcgi/",
                        "socket" => "/var/run/lighttpd/fastcgi.python.socket")
  • make sure the python file has correct execution rights and restart lighttpd daemon.
sudo systemctl restart lighttpd.service

Updating daemon and web interface on Linux

You have prevoiusly installed the callblock application and would like to update it to the lastest version. Make a backup of your configuration (/etc/callblocker), the installation will not overwrite it, but you never know.

  1. In case you have still the installation git checkout:
cd callblocker
git pull
make clean all

Else you do not have the installation git checkout anymore:

git clone
cd callblocker
automake --add-missing --foreign
./configure --prefix=/usr --sysconfdir=/etc
make all
  1. Double check your settings.json. Hints:
  • v0.0.7: switched from php to python web backend
  • v0.9.0: prefix "from_" has been removed from "from_domain", "from_username" and "from password"
  • v0.11.0: moved from jessie to stretch, for jessie use the 0.10.x release
sudo systemctl stop callblockerd
sudo make install
sudo systemctl daemon-reload
sudo systemctl start callblockerd
  1. Double check your web configuration and do:
sudo systemctl restart lighttpd.service

File Layout

When installed on Linux, the following file layout is used:

drwxr-xr-x www-data www-data /etc/callblocker                              # configuration
-rw-r--r-- www-data www-data /etc/callblocker/settings.json                # configuration file
drwxr-xr-x www-data www-data /etc/callblocker/blacklists                   # put your blacklists here
drwxr-xr-x www-data www-data /etc/callblocker/whitelists                   # put your whitelists here
drwxr-xr-x www-data www-data /etc/callblocker/cache                        # used for caching online request
-rwxr-xr-x root     root     /usr/bin/callblockerd                         # daemon
drwxr-xr-x root     root     /usr/share/callblocker                        # python helper scripts

When using the web interface:

drwxr-xr-x root     root     /usr/var/www/callblocker                      # web interface
-rw-r--r-- root     root     /usr/var/www/callblocker/app.css              # css
-rw-r--r-- root     root     /usr/var/www/callblocker/index.html           # start page
-rw-r--r-- root     root     /usr/var/www/callblocker/js/app.js            # javascript
drwxr-xr-x root     root     /usr/var/www/callblocker/js/vendor            # 3rd party libraries:
drwxr-xr-x root     root     /usr/var/www/callblocker/js/vendor/dijit      # - dijit
drwxr-xr-x root     root     /usr/var/www/callblocker/js/vendor/dojo       # - dojo
drwxr-xr-x root     root     /usr/var/www/callblocker/js/vendor/dojox      # - dojox
drwxr-xr-x root     root     /usr/var/www/callblocker/python-fcgi          # web backend
-rwxr-xr-x root     root     /usr/var/www/callblocker/python-fcgi/
-rw-r--r-- root     root     /usr/var/www/callblocker/python-fcgi/
-rw-r--r-- root     root     /usr/var/www/callblocker/python-fcgi/
-rw-r--r-- root     root     /usr/var/www/callblocker/python-fcgi/
-rw-r--r-- root     root     /usr/var/www/callblocker/python-fcgi/

Configuration file

The documentation of the configuration file "settings.json" is located here.

Offline blacklists

Through the web interface you have the possibility to maintain your own blacklist. Additionally there is the possibility to download automatically an extern maintained blacklist for later offline usage. You will need to setup a cronjob for this task to download the blacklist periodically.

Currently the following blacklists are supported:

Name Site Description Mostly USA and Canada (+1) Switzerland (+41)

The following cronjob will download each day the blacklist provided by ktipp_ch:

0 0 * * * /usr/share/callblocker/ --output /etc/callblocker/blacklists/ >/dev/null 2>&1


There are two ways to connect the call blocker application with your phone system, depending if it is VoIP or analog.

Setup using Fritzbox with an IP-phone

  • create in the Fritzbox a new IP-phone
    • open your web browser and navigate to the URL
    • in the menu "Telefonie -> Telefoniegeraete" click on "Neues Geraet einrichten"
    • choose "Telefon (mit und ohne Anrufbeantworter)" and click "Weiter"
    • choose "LAN/WLAN (IP-Telefon)", for name use for example "callblocker" and click "Weiter"
    • choose a password, remember it and click "Weiter"
    • choose "alle Anrufe annehmen" and click "Weiter"
  • setup the IP-phone in the call blocker configuration (/etc/callblocker/setting.json):
    • edit the section sip -> accounts
    • "domain": ""
    • "username": "your username"
    • "password": "your password"
    • make sure the account is enabled and the other fields are ok for you

Setup using an analog phone

  • attach the USB modem to the Raspberry Pi
  • use dmesg to find the device name /dev/<name>
  • setup the Analog phone in the call blocker configuration (/etc/callblocker/setting.json):
    • edit the section analog -> phones
    • "device": "your device name"
    • make sure the account is enabled and the other fields are ok for you


Symptom: It is unspecific not working.

  • double check all installed files, with its locations and permissions. See file layout
  • make sure lighttpd and callblockerd are running.
sudo ps aux | grep -E 'lighttpd|callblockerd' | grep -v 'grep' # shows: 2 lines
  • check for possible errors/warning.
sudo journalctl _SYSTEMD_UNIT=callblockerd.service
  • increase log levels: "log_level" to "debug" and/or "pjsip_log_level" to 2. See documentation of configuration file for more info. And restart callblockerd.
sudo vi /etc/callblocker/settings.json
sudo systemctl restart callblockerd.service

Symptom: Web interface is not working.

The web interface is running within lighttpd, double check the web configuration of this deamon.

  • also look into the seperate log file:
sudo cat /var/log/lighttpd/error.log
sudo journalctl -xn _SYSTEMD_UNIT=lighttpd.service
  • make sure the python file has correct execution rights
sudo chmod a+x /usr/var/www/callblocker/python-fcgi/

Symptom: Configuration done within the web interface is not saved persistent.

The web interface is running within lighttpd, this deamon is using "www-data" as user and group. Make sure that this process has access to the configuration file (see file layout).

sudo chown -R www-data.www-data /etc/callblocker/

Symptom: Caller log and diagnostics stay empty within the web interface.

Make sure journal is active and working and the web interface has access to the journal.The web interface depends on functionality provided by systemd journal.

# switch to systemd journal
sudo apt-get purge rsyslog logrotate libestr0 liblogging-stdlog0 liblognorm1
sudo vi /etc/systemd/journald.conf: #Storage=auto -> Storage=auto
sudo rm -rf /var/log/* # optional, you will lose all existing log entries (old format)
sudo mkdir /var/log/journal
sudo reboot # required to finished the switch

# allow web interface access the journal
sudo usermod -a -G systemd-journal www-data
sudo systemctl restart lighttpd.service

# manual verify that journal is working
sudo journalctl _SYSTEMD_UNIT=callblockerd.service