Legal analysis: in the process of cell phone forensics, the first step in the work from the cell phone of all relevant sources of evidence to take the clue value of electronic evidence from the cell phone SIM card, memory, external storage cards and mobile network operators in the business of the database together constitute the cell phone forensics in the important source of evidence. Investigation and forensic personnel can be based on the SIM card registered cell phone number to the call records database data search, in order to get the number of all the call records and SMS records, in addition to cell phone IMEI number to search for user registration information in the database of this cell phone user registration information and call records. In the implementation of the "real name system of cell phones", the investigation and evidence collection personnel can also be simple to the user registration information database and the data in the database of the resident identity card system to compare and analyze the relevant data. However, due to the network operator's business database is characterized by a large amount of data, fast update, so the investigation and evidence collection personnel should be as soon as possible to complete the extraction of evidence on the network operator's relevant business database, so as to avoid the required data to be updated or deleted.

Legal basis: "Chinese People's **** and the State Criminal Procedure Law" Article 52 The trial staff, procurators, investigators must be in accordance with the legal procedures, to collect a variety of evidence that can confirm the guilt or innocence of suspects and defendants, and the severity of the crime. It is strictly forbidden to extort confessions by torture or to collect evidence by threats, inducements, deception or other unlawful methods, and no one may be forced to prove his or her guilt. It must be ensured that all citizens who are related to the case or have knowledge of the facts of the case have the conditions to provide evidence objectively and adequately, and may be absorbed to assist in the investigation, except in special circumstances.