Technically, voice over lan is not required to use IP as the underlying protocol. For example, on an ethernet lan you could use fundamental ethernet packets to convey voice data directly without using IP or any other higher level protocols.
As a practical matter though, sinip is correct: IP is the standard for conveying voice data on networks.
Voice over LAN is same than Voice over IP, but the concept "Voice over IP" is more broad, voice over ip you can see in net WAN, LAN, etc and in different protocols (ATM, SDH, ETHERNET, FDDI, etc)
I need layer three for traffic paquet of VoIP, but I need conected at switch L2.
Voice over IP is same as Voice over LAN, the main difference is Voice over LAN is used in LAN networks using IP protocols whereas Voice over IP is used in any broadband stream, and lastly VoIP has many functionalities than Voice over LAN.