Nowadays, authentication of wireless users is mandatory for legal  reasons.
For free WLAN Hotspot, the simplest authentication method is to  send an SMS code to the user's phone number.
secuPASS  ® is a simple SMS authentication online service for free WLAN Hotspot. 
The 
secuPASS  ® authenticated user is stored in the access points systems log using his mobile phone number. The log can be saved on a USB key installed in the authentication device, or on a Syslog server.
Specifications
secuPASS  ® offers an easy authentication service
for free Wifi using SMS code.
 
secuPASS  ® is an online service and uses the
swiss provider 
ASPSMS  in order to send SMS
(
http://www.aspsms.com/).
You will need to open an account by them and
you will have to buy some SMS credits.
 
Learn moreSubscribe for the secuPASS service
 								Even if it’s preferred, you don’t need to have a
fixed IP address in order to use this service.
A dynamic FQDN (like a No-IP  account)
is enough.
 
You need to subscribe for one service
for each node (one node per FQDN / IP address).
SubscribeSupport
 								Documentation and support are available online.
 
Learn more