The IEEE standard for multimedia in a local area network (LAN) is based on ISLAN-16T and it incorporates an integrated services digital network (ISDN) phone system with LAN-based ethernet for mixed data transmission. The IEEE standard, designated 802.9a for LANs and metropolitan area networks (WAN) is a physical layer standard that defines the standard's media access control and physical layer. In addition to this, 802.9a specifies a signaling layer based on ISDN protocols using existing 10Base-T infrastructures, allowing the technology to be implemented in an existing or legacy network, avoiding replacement of the network infrastructure and equipment.