There are bands that require strict occupancy rules. Equipment can only be sold in countries that use those frequencies that abide by the standards. These standards exist for that reason. 868MHz is one such band that has strict usage rules. Any equipment using the band CANNOT transmit on that band for more than 1% of the time. This allows upto 100 other pieces of equipment in the immediate vicinity to use the same band. There are several wireless alarms using this band at the moment and they have superb RFI detection and jamming signal algorithms.