I think there used to be some no cost providers, but I don't know of them. Even if GV changes to a pay service, all you have do is port your number to whoever is the lowest cost provider.
Look back in time at how much you pay to have a landline. If you can have that same service at no cost for one year you come out ahead. Or even for a few months. For one of two lines I used to keep the lowest cost landline service possible. It was a about 28 USD per month. What I get now from GV (Caller ID, Call Waiting, Voice to Text, Call Forwarding, VM, Text notification of VM, Telemarketing call flagging, unpublished name, etc.) would have cost $65 +, and that is before any long distance charges, which of course is no cost to the US and Canada. The level of call forwarding alone that GV provides could cost 50 to 100 USD per month.
P.S: If I were a SIP provider other than GV, that would be a beneficial story to keep out there in the wild, "GV may not be free forever..."