Is contract enforceable if employer did not sign it?

My husband was recently layed off from the tv station he was working for. When they initially hired him, they gave him a 2 year contract that stated if he was terminated for no just cause, they had to give 90 days notice or pay in lieu of. When they gave him the contract, they told him to read over it, and if he agreed to the terms to sign it and return it to his boss-which he did and has been working under the terms of this contract for 6 1/2 months. When his boss let him go last week, he said "I do not recall the specific severance package in your contract so go home and read your contract in regards to how much severance you will receive". He read it and again, it indicated either 90 days notice or pay in lieu of. The next day, he called HR to get the specifics, and they told him he was getting 2 weeks severance b/c he did not have a contract. He said-I do, it's right in fromt of me and states 90 days severance. They responded that his contract is not valid b/c all the appropriate people at the company did not sign it. This is the only paper he ever received in regards to the terms of his employment (ie salary, position etc). I have 2 questions:
1.Is this fraud that they gave him a contract they did not sign (I believe intentionally).
2. Is this contract enforceable since he has been working under the terms of this contract for over 6 months?
Please help!