A communication system operates in the first power state during a communication session. The system transitions from the first to a second power state, when a first predefined time period expires after transfer of a packet and before a transfer of a next packet, for any of and no more than a first N packets in the communication session. Alternatively or in addition, the system transitions from the first to the second power state when: (a) the first predefined time period expires after transfer of a packet and before transfer of a next packet in the communication session and (b) the size of each packet transferred thus far in the communication session is not greater than S.