I have the Obi202 and it rings into a Panasonic cordless phone with Caller ID. No matter how the call originated (AT&T land line, AT&T cell phone, T-Mobile cell phone or Virgin Mobile) the phone displays "Out of Area."
This issue has been referenced in other posts, but the responses I was able to find are all over the map. I don't know what the definitive answer on this issue is.