It is not clear how Oklahoma could have obtained a default child support order against someone in prison. The order should be void.
Most states do that with extreme limits - time constraints on filing - just like OK. My guess is that if you check closer, you may find that Arkansas is the same way. It may only be 30 days from the birth of the child.
What Pierce didn't realize, and what nearly 10 million American men have discovered to their chagrin since the welfare reform legislation of 1996, is that when the government accuses you of fathering a child, no matter how flimsy the evidence, you are one month away from having your life wrecked. source