HPNA can operate simultaniously with other services such as POTS on a single pair.It utilizes FDM (Frequency Division Multiplexing), which gives each service its own frequency spectrum over the line. I beleive the frquency is between 2 and30 mhz for the new version of HPNA (2.0).HPNA is specified to 10 mibs,that im aware of,and also run using CSMA\CD access method. Just for thought,your POTS service is at about 20 hz to 3.5 khz.The quality of your existing phonelines is definatly a factor for this type of network.Inspect the condition of the existing phone wiring first,and note type,splices,cuts,etc.It would have to in really bad shape to not run 10 mibs.At which point you can decide to take the chance on your exisitng wiring for your HPNA network.I would at least plug in a phone in each of the jacks your plugging a PC into,and check for tone,so you know they are all operable to avoid untimely troubleshooting later when a PC on your network doesnt talk.How many PC's are you connecting?Good Luck!