Guerrilla VoIP

From Hackerspace ACKspace
Jump to: navigation, search
Project: Guerrilla VoIP
Featured: No
State Active
Members xopr
GitHub No GitHub project defined. Add your project here.
Description low cost communication node
Guerilla voip in use.jpg


Try to:

  • connect anything that can carry a voice channel, or, preferably, a data channel
  • feed from any (cheap/renewable) energy source
  • make it weather resistant and transportable
  • consider standards


connect anything that can carry a voice/data channel

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

feed from any energy source


  • solar power support
    this is the easiest renewable energy source: panels are affordable and the sun is more ore less abundant.
  • battery backup support preferred
    a sealed lead acid (SLA) battery is affordable, easy to come by, easy to charge and maintenance free. Their downside is bulkiness and weight. 12V 7Ah is a good ratio between weight and energy.

weather resistant and transportable

Make sure the electronics are encased in a sturdy, weatherproof housing. It should also be easily transportable and affordable.

The best thing that will apply is an ammo case from an army surplus shop.

consider standards


  • mains input: 100-250V~ 50-60Hz
  • internal voltage rails:
    • 5V: standard for raspberry pi and some network devices
    • 12V: battery 'standard' and standard for other network devices
    • 48V: Power over Ethernet and telephony standard


  • MC4 connectors: solar
  • Anderson powerpole plug: UPS
  • cigarette lighter plug (ANSI/SAE J563): cars
  • powerlet plug (ISO 4165): alternative/old cars and motorcycles
  • double banana plug (19mm/0.75" spacing): equipment standard

current version

The current version has:

  • ammo box
  • 7Ah SLA battery
  • banana/screw terminal
  • weatherproof ethernet outlet
  • 12-volt cigarette lighter receptacle
  • 3D printed insert
  • fuse box
  • switches for device targeting power and power state preview
  • Netgear GS110TP (8xPoE + 2xSFP)
  • a couple Telephone system:Cisco PoE hack cable, but the switch supports pre-standard PoE
  • electronics:
    1 on-off-on momentarily 3-pole double throw: battery/external/outlet input and voltage rail status
    3 on-off-on switch 1-pole double throw: source-destination rail (application/charge)
    6 fuses (1, 1, 4, 4, 7.5, 7.5) for 5V rail, 10-15V rail, 48V rail, outlet, battery, ext. power
    3 LEDs 2v 20mA
    6 resistors (4x600R, 225R, 150R)
    2 10W resistors (2R, 20R)
    2 schottky diodes 4-10A
    2 DC-DC converters (5V 3A, 48V 1.25A)
    3 crowbar circuits (5V, 15V, 48V)


  • upload models and schematics
  • 3D print inlay for Switch/PI holder
  • install fuses and crowbar circuit
  • install state leds
  • install step-down converter 12->5V
  • install step-up converter 12v->48V
  • Raspberry PI or Orange PI
  • NL dialplan (FS/Cisco)



It is possible to power the PoE switch with two USB-C powerbank for off-the-grid usage, ideal for a hackers on a bike tour. All you need is:

ideally, pass-through/UPS USB-C power banks like the Zmi PowerPack No. 20 Model QB826G would be best, but they're 4 times as expensive

See the PCB in this picture to get an idea.

Note that since the banks are connected in series, one shield/ground is lifted 20 volts; don't let any USB ground touch the other powerbank's ground in any way (also goes for the USB-A ports in this set-up; it will fail spectacularly)!



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 (€99.64) 48v 4W 8/8 8 2
TP Link TL-SG108PE €65 48v 5.2w 8/8 4
Siemens Gigaset N510 IP PRO £53.94 (€65.39) 6.5v 1.2-1.3W 1/? 6hs,4sc

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 5v 10W 1/0 2×FXS
Sipura SPA3000 5v 7.5W 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]
A) Netgear, Pi, 7940, Gl.inet SLA battery 12V 12W[3]
B) Netgear, Pi, 7940, Gl.inet, Gigaset SLA battery 12V 13.3W[3]
C) Netgear, Pi, 7940, FritzBox SLA battery 12V 16.3W[3]
[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, using Netgear GS110TP PoE, Raspberry Pi, Gl.inet, Siemens Gigaset N510 and/or Fritz!box

solar panel and battery

Did some rough estimations with a 15 Watt solar panel (using a Unified Clear-Sky Solar Prediction Model script): on a good summer day it will yield 240W in 17 hours (slightly below 15 megajoule), and on a clear winter day it will yield 25W in 7 hours (630 kilojoule).

A 12v SLA battery is full with >12.85V, empty with 12.00V (at 25% capacity) and fully depleted at 11.80V. I came to the conclusion that the effective energy is about 9.5×Ah; given a 7Ah battery, this will yield about 66.5Wh.

Given the hardware setups described in the previous paragraph (note that these values are theoretical maximums):

scenario battery run time solar+battery run time (winter/summer)
A 5:30h 7:35h/25:30h
B 5:00h 6:55h/23:00h
C 4:00h 5:35h/18:45h

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

log and ideas

A list of ideas to consider:

  • modular 3D insert for different single board computers
  • extra network outlet (since a single one is more or less useless)
  • float or CC/CV charger, MPPT solar charger
  • external antenna mount
  • temperature monitor

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


Some random links: