Instruct: Classify a given review as either positive or negative.
Query: AT&T 9520

I bought this phone for its sleek design and affordable price. The first problem I encountered, after the warranty had expired, is the famous battery problem these phones face. No amount of charging or battery swapping could remedy the poor performance of the phone. I would be cut off 15 minutes into the conversation. The second problem I recently faced was the degradation of the sound quality down to unintelligible sounds. Finaly the phone started muting my conversation at random intervals. Very poor performance for a phone.