diff --git a/README.md b/README.md
index 56d1768..652c424 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,70 @@
 # IMSI-catcher
-This program show you IMSI numbers of cellphones around you.
+This program show you IMSI numbers of cellphones around you.  
+  
+/!\ This program was made to understand how GSM network work. Not for bad hacking !  
+  
+  
+What you need
+=============
+1 PC with more than 3Go of RAM to compile gr-gsm  
+1 USB DVB-T key (RTL2832U) with antenna (less than 15$)  
+  
+  
+Setup
+=====
+
+```
+cd /tmp
+sudo apt-get install gnuradio git python-scapy
+git clone https://github.com/pybombs/pybombs.git
+cd pybombs
+```
+/!\ when "./pybombs config" set "/usr/local" when it ask "prefix" :  
+prefix [/tmp/target]:/usr/local  
+```
+./pybombs config
+```
+```
+sudo ./pybombs install gr-gsm
+echo "[grc]
+local_blocks_path=/usr/local/share/gnuradio/grc/blocks
+" > ~/.gnuradio/config.conf
+```
+
+Run
+===
+  
+In terminal 1  
+```
+sudo python simple_IMSI-catcher.py
+```
+
+In terminal 2  
+```
+airprobe_rtlsdr.py
+```
+Now, change the frequency and stop it when you have out put like :  
+```
+15 06 21 00 01 f0 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+25 06 21 00 05 f4 f8 68 03 26 23 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
+49 06 1b 95 cc 02 f8 02 01 9c c8 03 1e 57 a5 01 79 00 00 1c 13 2b 2b
+...
+```
+Now, watch terminal 1 and wait. IMSI number should appear :-)  
+  
+Doc : https://fr.wikipedia.org/wiki/Global_System_for_Mobile_Communications  
+Example of frequency : 9.288e+08 Bouygues  
+  
+You can watch GSM packet with  
+```
+sudo wireshark -k -Y '!icmp && gsmtap' -i lo
+```
+  
+Links
+=====
+
+Setup of Gr-Gsm : http://blog.nikseetharaman.com/gsm-network-characterization-using-software-defined-radio/  
+Frequency : https://fr.wikipedia.org/wiki/Global_System_for_Mobile_Communications  
+Scapy : http://secdev.org/projects/scapy/doc/usage.html  
+IMSI : https://fr.wikipedia.org/wiki/IMSI  
+Realtek RTL2832U : http://doc.ubuntu-fr.org/rtl2832u and http://doc.ubuntu-fr.org/rtl-sdr