A discovered NFC-B listen mode device is put to SLEEP state only when there are one or more NFC-B listen mode devices yet to be discovered. An optimal value for the number of time slots indicated in a command is computed based on a combination of whether an empty time slot was detected and/or collision was detected and/or an NFC-B listen mode device was discovered in a discovery cycle. The compliance with the NFC Forum Activity Specification allows the direct activation of an NFC-B listen mode device, and thus speeds up the data transfer phase and consumes much less power.