Guerilla VoIP

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Project: Guerilla VoIP
State Planned
Members xopr
GitHub No GitHub project defined. Add your project here.
Description low cost communication node
Guerilla voip in use.jpg


Some essential hardware broke; need to rebuild it and add some extra safety features

Create a low cost communication node (with VoIP as a base), trying to connect as many as possible types of links, for example:

  • copper/fibre/WiFi network
  • DECT/POTS telephony
  • HAM radio (or preferrably, CB radio: 27MC/PMR)
  • copper/WiFi/USB uplink

It also could need some of the following functionality:

  • PoE service (to drive phones, remote switches/accesspoints)
  • battery supported/powered (in case of power failures/lack of power)
  • Efficient power converter(s) when running on battery
  • sturdy compact waterproof casing


So to make the first prototype, I chose the following:

  • ammo box
  • 7Ah battery
  • step-down converter 12->5V
  • step-up converter 12v->48V
  • Fritz!Box 7270 (NAT, FxS, FxO, DECT)
  • two Raspberry Pis running FreeSWITCH (external queue, internal SCCP server), DHCP and TFTP
  • Netgear GS110TP (8xPoE + 2xSFP)



HW price range voltage power consumption copper/Gbit PoE fibre VLAN 2.4GHz 5GHz DSL ISDN POTS DECT USB
Fritz!Box 7270 € 50-213 5.5-15v 4.3W - 5.3W 4/0  ? 2×FXS / 1×FXO 5 (6?)hs 1×2.0
GL-Inet €22-30 5v 1W 2/0 1×2.0
TP WR-703n €17-25 5v 1W 1/0 1×2.0
Netgear GS110TP €126-140 48v 4W 8/8 8 2
TP Link TL-SG108PE €65 48v 5.2w 8/8 4

hard phones / ATAs

HW price range voltage power consumption copper/Gbit PoE VLAN SIP lines extensible tested on FreeSWITCH
Cisco 7905 € 10-50 48v 1/0 1(?)
Cisco 7910 48v 1/0 6(?)
Cisco 7940/7960 € 10-50 48v 5W 2/0 2/6
Cisco 7941/7961 48v 2/2(?) ✓(?) 2/6
Avaya 4620SW 48v 2/0? ✓(?) ✓(?)  ?
Linksys PAP2T 9v? 1/0 2×FXS
Sipura SPA3000 9v? 1/0 1×FXS 1×FXO

some power tests

hardware power source U I Papproximated
two Raspberry Pis, step down drill battery pack 12.6V[1] 330mA 2×2W
Cisco CP7940, step up drill battery pack 12.6V[1] 360mA - 450mA 5W
Fritz!box (wifi off), direct lab power supply 12V 360mA (idle) - 440mA
(42% - 52%, top ~880mA)
4.3W - 5.3W
15V 250mA (idle) 3.8W
Netgear GS110TP PoE, step up lab power supply 12V 330mA 4W
Netgear GS110TP PoE +
Cisco CP7940, step up
lab power supply 12V 740mA 9W
Complete set: 2 RasPis,
Fritz!box, switch,
phone + cellphone charging
lab power supply 12V 2000mA 24W
13.8V 1600mA 22W
cellphone charging lab power supply 5W[2]
Minimal setup:
[1] Approximated by calculating deviation from the lab power supply combined values, which was about 5% off 12V
[2] Approximated by subtracting all calculated items from the complete setup
[3] Approximated by just adding up individual items

interesting facts

  • Fritz!box has a switching regulator to 5V tested between 5.5V and 15V (drops off at 5.3V idle and elco at power supply segment is rated 16V)
  • PoE hack adapter connected pin 1 (white-orange) and pin 3 (white-green) with 22K resistor.
  • if the pre-standard CP-79x0 is connected using the PoE adapter hack, the Netgear GS110TP doesn't power, when you unplug it, it will enable power within 5 seconds; plug in, and the phone boots.
  • if you configure the administrative VLAN, the phone will fetch a DHCP lease on that VLAN, allowing you to seperately set up dnsmasq on a Raspberry Pi


  • Fritz!Boxes
7270 (ADSL2+, 1×USB 2.0, a/b, S0 [FXO], 2×FXS, S0-bus, n×DECT, 4×100Mbit, 2.4GHz or 5GHz, 64MB RAM)
7340 (ADSL2+, VDSL, 2×USB 2.0, a/b, S0 [FXO], 2×FXS, n×DECT, 2×Gbit, 2.4GHz or 5GHz, 128MB RAM)
7340 (ADSL2+, VDSL, 2×USB 2.0, a/b, S0 [FXO], 2×FXS, S0-bus, n×DECT, 4×100Mbit, 2.4GHz and 5GHz, 512MB RAM)
  • DECT phones
2×Siemens AL28H
2×Siemens A420 (PsychiC has one)
2×Philips CD6552B
2×Philips CD1302S
1×Philips DECT1221S
1×Profoon PDX2900
+ what's not yet inventoried at the space


  • the first version works, but still needs some manual labor
  • Telephone system:Cisco PoE hack cable
  • Cisco NL dialplan
  • tested with battery; float charging device still has to be made (haven't measured how long it would run on a single charge though, but enough time to do some important phone calling)

Also, I've been playing with the Banana Pi, since the Raspberry Pi sometimes chokes on input digits. Here is a log/some steps to reproduce

get the basics

apt-get install vlan dnsmasq make curl

create and install FreeSWITCH


cd /usr/src
curl > Makefile

If you want to compile and install STABLE branch, edit the above Makefile and add " -b v1.4 " just after the word "clone".

make && make install
  • (you can kill time by doing the other chapters)

create user 'freeswitch', add it to group 'daemon' and change owner and group of the freeswitch installation

cd /usr/local
adduser --disabled-password  --quiet --system --home /usr/local/freeswitch --gecos "FreeSWITCH Voice Platform" --ingroup daemon freeswitch
chown -R freeswitch:daemon /usr/local/freeswitch/
chmod -R ug=rwX,o= /usr/local/freeswitch/
chmod -R u=rwx,g=rx /usr/local/freeswitch/bin/*

prepare VLAN

modprobe 8021q
lsmod | grep 8021q
echo 8021q >> /etc/modules
vconfig set_name_type DEV_PLUS_VID_NO_PAD

set-up network and VLAN

vi /etc/network/interfaces
auto lo
iface lo inet loopback

auto eth0

# dhcp configuration, used in normal operation (this connects to your internet)
iface eth0 inet dhcp

# static ip configuration, used for stand-alone preconfiguring factory-reset phones
#iface eth0 inet static
#	address
#	netmask
#	gateway

# operational VLAN 11 (pick any), for usage with VoIP
auto eth0.11
iface eth0.11 inet static
    vlan-raw-device eth0


vi /etc/dnsmasq.conf
# uncomment to enable dhcp server on eth0, used for stand-alone preconfiguring factory-reset phones
# operational VLAN 11 (pick any), for usage with VoIP

# Choose different ranges for each (V)LAN

# Most likeley not needed

# Enable dnsmasq's built-in TFTP server to serve config files

# Set the root directory for files available via FTP.

Create the /srv/tftp directory and put the configs and firmwares in it. Here is a config generator you can put in there (sorry, can't provide the firmwares since "I don't have them").

service dnsmasq restart


/etc/init.d/dnsmasq restart

toggleconfig script



  service dnsmasq stop > /dev/null
  #nohup sh -c "invoke-rc.d networking stop; sleep 2; invoke-rc.d networking start"
  invoke-rc.d networking stop > /dev/null
  sleep 2
  invoke-rc.d networking start > /dev/null
  service dnsmasq start > /dev/null


  # reset gpio pin and led
  echo "11" > /sys/class/gpio/unexport
  echo 0 > /sys/class/leds/led0/brightness
  echo none > /sys/class/leds/led0/trigger

  echo done

if [ ! -f /etc/dnsmasq.conf.regular ]; then echo "/etc/dnsmasq.conf.regular does not exist"; exit; fi
if [ ! -f /etc/dnsmasq.conf.config ]; then echo "/etc/dnsmasq.conf.config does not exist"; exit; fi
if [ ! -f /etc/network/interfaces.regular ]; then echo "/etc/network/interfaces.regular does not exist"; exit; fi
if [ ! -f /etc/network/interfaces.config ]; then echo "/etc/network/interfaces.config does not exist"; exit; fi


echo "11" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio11/direction

while true; do

  echo "regular mode"
  echo none > /sys/class/leds/led0/trigger

  # regular config files
  cp /etc/dnsmasq.conf.regular /etc/dnsmasq.conf
  cp /etc/network/interfaces.regular /etc/network/interfaces


  while [ `cat /sys/class/gpio/gpio11/value` -gt 0 ]; do
    echo 1 > /sys/class/leds/led0/brightness
    sleep 0.05
    echo 0 > /sys/class/leds/led0/brightness
    sleep 3

  echo "config mode"
  echo "heartbeat" > /sys/class/leds/led0/trigger

  # regular config files
  cp /etc/dnsmasq.conf.config /etc/dnsmasq.conf
  cp /etc/network/interfaces.config /etc/network/interfaces


  while [ `cat /sys/class/gpio/gpio11/value` -le 0 ]; do sleep 3; done


preconfigure phone

  • Connect the phone directly using a (optionally crosslink) ethernet cable.
  • Power the phone, and hold # until the red (mute) light is off and the phone states: "Reset sequence detected"
  • type 123456789*0#, and when asked to keep network config, choose 2=no
  • once the new firmware is loaded (Freeswitch is not running, so it won't connect), press 'settings' (checkbox button at the bottom right)
  • go to Admin. VLAN ID
  • type **# to unlock the setting, and press 'edit'
  • type in your voice VLAN (11 like the configs say)
  • press validate, and save
  • dnsmasq and interfaces configs can now be restored (no dhcp on eth0, only eth0.11)
  • nohup sh -c "invoke-rc.d networking stop; sleep 2; invoke-rc.d networking start"


  • work out 'modus operandi': multiple config files switchable by phone
  • work on dual linux config with GPIO hardware switch
  • test the fibre ports
  • add homeplug as a proof of concept
  • design and create (or buy) small-sized float charger (13.8V 2A) with overcurrent protection, if needed