No need. According to the inquiry method, the detention center needs to be present for identity verification and signature confirmation in the process of handling the card to ensure the identity of the card holder is true. All cards have magnetic cards, which will display personal information when used. You don't need to sign the card, just open the card and leave with your belongings. Holding a card in the detention center is a service provided by the detention center, which aims to facilitate the detainees to purchase daily necessities and communication needs.