WhatsSpy Public requires a secondary WhatsApp account. Once the tracker is started, you will not be able to receive any messages over WhatsApp for this phone number. You need to register at WhatsApp to retrieve a secret which you will need later when setting up WhatsSpy Public.
There are various methods, listed ascending based on experience since not all methods will work for you.
Notice sometimes you don't seem to receive a SMS. In this case wait a few days to try again.
Notice sometimes WhatsApp returns temp_unavailable. This means that WhatsApp cannot register your number and you should wait (one day, few days, no-one knows).
Warning do not use watools.es. Your number will be blocked instantly.
At the moment WhatsApp seems to ban numbers using old WhatsApp versions (probably because they are updating their infrastructure for WA 1.6). The method that is confirmed working is via a jailbroken iPhone or rooted Android APK. Use WART/registerTool.php or yowsup-cli at your own risk!
1.1) Getting a phone number
You need a phone(number) over which you can receive SMS or voice calls for the WhatsApp activation. You can try to register your land line, or just buy a 5 euro SIM card and register that phone number at WhatsApp. Do not use some shady SMS service, this won't work.
1.2) Activation at WhatsApp with your secondary phone number
You have four methods:
Use a supplied PHP script registerTool.php that will guide you through the steps.
Using yowsup-cli (commandline tool)
Use WART, a Windows registration tool which allows you to retrieve the secret via a GUI.
Activate WhatsApp on your jailbroken iPhone or rooted Android phone and retrieve the secret via this script (for iPhone users) or the following APK (for Android users).
1) registration via the registerTool.php script
In case of registration via the registerTool.php script you need to execute the following steps:
First make sure you have downloaded WhatsSpy Public on your Linux machine (Assuming you installed it in /var/www/whatsspy/).
Execute cd /var/www/whatsspy/api/whatsapp/ && sudo php registerTool.php (use chown -R <your-username> /var/www/whatsspy in case you get an "Could not open ..." error).
Enter your phonenumber that you want to use for the WhatsSpy Public tracker.
number needs to be without any prefix 0's. 0031 06 120.. becomes 31 6 120.. (no 0's prefix for both the countrycode and phonenumber itself).
number may only contain digits. Spaces, plus or any other special character are NOT accepted. Example: 316732174
Request activation via SMS and wait for a SMS to arrive at the phone (try voice if you did not get the SMS).
Enter the retrieved code in the script without any dashes (only the digits!).
Write down the secret (it's the one-line of strange characters ending with an =).
Did you get [status] => fail [reason] => bad_param after choosing SMS or voice? Make sure you entered the number correctly, have a proper internet connection or try another number (could not reach service provider of the phonenumber)