With OBiLine, you could make your OBi202 connect to the PSTN.
https://www.obitalk.com/forum/index.php?topic=6382.0Alternatively you could trade your OBi202 for an OBi110 as a private deal. Since your OBi202 is more valuable, you might be able to work out the other guy paying postage, or some such. A straight trade would get a more eager taker, especially if you could make the swap locally.
It is not clear why you think the PSTN line would be more resistant to expensive calls. I would think it to be the opposite... you can limit your GV costs by not over-funding your GV account. Do you mean "I would also like to restrict all (outgoing calls to [only using] the analog telco line)" vs "I would also like to restrict (all outgoing calls [that try to go] to the analog telco line)"
Otherwise, your post seemed to be correct. Ideally, define what you would like, look through previous dialing string posts, and post your proposed solution together with your description of what you are trying to achieve.