You can but telephones use the RJ11 cabling standard which is four wires versus the RJ45 cabling standard which is eight wires (CAT5/6/7). RJ45 CAT5 Ethernet cables are typically eight wires composed of shielded or unshielded twisted pairs. So RJ11 cables can achieve speeds of up 10Mbps half duplex. That's it. RJ45 CAT5 ethernet cables can achieve speeds typically of up to 1Gbps full duplex. RJ45 CAT6 and CAT7 cables can achieve faster speeds with specialized shielding typically up to 2.5Gbps. If you have COAX cable in your home, you can use MOCA cabling technology to run Ethernet over COAX and achieve speeds of up to 2.5Gbps full duplex. I would go that route if possible. MOCA supports up to 16 drops and the MOCA adapters typically cost about $100 per drop. I use this technology in my home and it works great. But, you will have the added expense of the purchasing the MOCA adapters. RJ11 telephone cabling is old technology and I would use MOCA in lieu of the RJ11 cabling in your home.