I’ve tested a way to disable the Apple Captive Portal Assistant/Sheet.  If you put www.apple.com into a DNS whitelist, the Captive Portal Assistant will not pop up after connecting to a Captive Portal Network.

 

After connecting to a wireless network, Apple tests connectivity by going to http://www.apple.com/library/test/success.html.  If successful, the user can launch Safari and start browsing.  If the test fails, then Apple launches their Captive Portal Assistant.

 

Regards,

Jim

It is not just iPhones, but also iPads.  We had similar issues with captive portal pages for store deployments for a large shoe vendor.  Apple, because the feel they can set standards, does not launch a "real" browser when the device encounters a captive portal as part of the sign on process.  Instead, it appears to be a "mini" browser with very limited capabilities.  So it won't handle redirections.  If you refresh the page you can sometimes see the browser page close and another open; the new one is the mobile safari browser. Macs don't have the problem because they launch a full browser.

Afshin, This is not an issue but the way that IOS devices operate. When a IOS device connects to the network with a Captive Portal it will open the landing page in what apple calls a 'Sheet' which closes upon being granted access to the network. The landing page is not displayed in Safari which means you cannot re-direct the browser to another page. Regards, Kevin