There are two common types of subpoenas. The first is a subpoena ad testificandum. This subpoena requires a person to orally testify before a court either by phone or in person. The second subpoena is a subpoena duces tecum. It requires a person or organization to provide physical evidence before the court. This type of subpoena is typically used for obtaining documents that are important to the case as a whole or to a specific issue of the case.