Force Log-Into WiFi

Hi,

When I select to join a WiFi, the iPhone automatically connects to it without taking me to the WiFi's login page that requires username and password. This may be fine in a lot of conditions but for situations where the WiFi owner has programmed their system to disconnect a user after certain time or when the phone goes to sleep or when you leave the facility and come back a day or so ago it can be a problem. The reason is that the iPhone shows that it is fully connected while many apps complain that there are no network connection.

So, how can I force the iPhone to take me to the WiFi's login page?

Thanks