Go to jail for not answering a citation!??!?

My brother was served a citation for child support. They always send him a citation and never a subpoena. She receives government aid and does not reside with the child in question. We believe that is why he never gets subpoena'd because then maybe she would lose all her support. In the citation it states to send a written doent stating he received the citation. He doesn't want to, he feel as though the judicial officer or attorney is trying to scare him (there is NO court order for child support at all) into paying. If he does not respond can they issue a warrant? The citation does not express any obligation to respond and also doesn't state that there will be a warrant issued if he fails to respond. If he doesn't respond, can they issue a warrant still? This is not a citation to appear in court! But to respond. What would happen if he didnt respond?