Does 7940 support the 802.3af? I know that 7940 supports PoE. But what about 802.3af? Aren't they pratically the same?
Nopes, it does not support 802.af. 7940 IP Phone only supports Cisco Proprietary Inline Power.
Though if you are using a Cisco switch that supports 802.af, it would even support Cisco Prop Inline power supply