The FCC on Tuesday warned that it will no longer tolerate hotels, convention centers or others intentionally interfering with personal Wi-Fi hotspots.

This issue grabbed headlines last fall when Marriott International was fined $600K for blocking customer Wi-Fi hotspots, presumably to encourage the guests to pay for pricey Internet access from the hotel.

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Marriott later asked the FCC for permission to block some Wi-Fi hotspots, citing security and performance issues related to its own Wi-Fi networks, but has since backed off that pursuit. Guests, as well as tech companies such as Google and Microsoft, came out in opposition to hotels blocking Wi-Fi hotspots.

In its strongly worded warning today, the FCC said it will "aggressively" investigate and act upon "unlawful intentional interference." Its Enforcement Bureau is investigating several complaints.

Not only did the FCC warn hotels and convention centers, but also network providers serving such establishments. It also emphasized that the sale of wireless jamming tools is prohibited.

If you suspect interference is taking place, you should contact the FCC here or call 888-CALL-FCC.