I have a 7911 IP phone that is connected to a DHCP server through SG 300-28 PoE switch, the switch is working as a Layer 2 switch. The IP phone can not get an IP address from the DHCP server, other PCs are connected to the same DHCP server through the same switch and can get IP addresses normally. Any suggestions to make the 7911 IP phone available of participating the same network, I will be appreciated.