Linksys PAP2-NA VOIP Analog Telephone Adapter (Unlocked) Factory Unlocked Linksys PAP2-NA Works with any voip provider who supports BYOD (Bring your own device) Tested with Callcentric , VOIP dot MS, Freephoneline , Vbuzzer and VOIPDISCOUNT DOES NOT work with Vonage, NOR Skype .