The Cisco ATA (Analog Telephone Adapters) allow you to use your existing analog phones and fax machines in the networked world. 

Models:

ATA186 - 2x RJ11 ports and 1x RJ45 port for network connection

ATA188 - 2x RJ11 ports, 1x RJ45 port for network connection and 1x RJ45 port for connection to PC or other "downstream" Ethernet device