Wi-Fi providers who redirect users' web browsers to their own log-in page may soon have to cough up cash if they want to continue using the technique - US network access software company Nomadix has patented it.

The patent, number 6,636,894, was granted on 21 October last year, but is applicable right back to 8 December 1999. It essentially describes systems that redirects portable-computer users who access a public network to the host's home page, irrespective of the user's browser settings and transparent to the user. The systems cover both wired and wireless access.

Almost all public Wi-Fi networks - and pretty much every one of them that charge users for access - operate such a methodology. No wonder Nomadix describes the technique as "fundamentally essential to the success of the rapidly growing Wi-Fi market".

Nomadix customers will inherently have a licence to use the technique, but WISPs who have developed their own redirection code, or have acquired it from other companies, will need to ensure they have permission to use it.

Nomadix will certainly be expecting them to. "Some [companies] copied what we've done," said Nomadix CTO, co-founder and senior VP, Joel Short, according to a Wi-Fi Networking News report. "We stand behind our intellectual property and now we're going to encourage those folks who provide that method to license the technology from us." ®