http://mydeviceinfo.g.comcast.net/ lists two 4-line eMTAs: the TM604G ( DOCSIS 2 ) and the TM804G ( DOCSIS 3 ), but these are only available for rental, not for retail purchase. Only a few eMTA devices are approved for purchase, and they seem to be 2-line only models.
Thanks for your feed back. The TM804G ( DOCSIS 3 ) can be bought online https://www.amazon.com/Touchstone-TM804G-Telephone-Without-Wireless/dp/B00ANAN6BW
but this is a 2 phone line modem 4 ethernet. Again thanks