Yes it works exactly the same as a POT (plain old telephone) line using the Obihai or other type of network adapter, although there are some limitations with some adapters. We use the OBi202 which allows us to use 2 phone separate "phone lines" at once. You can actually use the OBi202 with up to 4 four numbers. I would love to use a provider other than Google, but they are free and have been for years now which keeps competitors out of the market.
thanks