About any VoIP provider that supports BYOD (Bring You Own Device) should work. You just need to shop around to find the services you want (outbound only or with an incoming number), the payment style you wish (pay as you go or monthly set rate), and the features you like (voicemail, CallerID with name, etc.). Once you sign up, you'll receive a username, password, and sip server to plug into the OBi and you should be good to go.
