Is it theft or robbery to suddenly escape in the name of making a phone call under the guise of a mobile phone?

First of all, from the definition of theft, this kind of behavior does not constitute theft. Theft is an act of secretly stealing a large amount of public or private property or stealing public or private property many times for the purpose of illegal possession. The act of theft is to steal in secret without the victim's knowledge. In this case, the suspect cheated the victim's mobile phone in the name of making a phone call, and then took it away under the witness of the victim, which did not conform to the form of secret theft. Therefore, this case cannot be regarded as theft.

Secondly, the key to distinguish crimes against property such as theft and robbery is to distinguish the nature of the act of illegally changing the legal possession of property, not the nature of the previous means. The act of illegally changing the legal possession of property is a harmful act that directly infringes on the criminal object, and it is also the core element of the crime constitution, which should be used to determine the crime. In this case, the act of illegally changing the legal possession of property is not the act of the victim lending his mobile phone to the defendant, but the act of the defendant fleeing the scene under the pretext that the victim made a phone call carelessly. In the sense of criminal law, the victim lent the mobile phone to the defendant, which did not change the legal possession of the mobile phone. It was after the defendant fled that the victim completely lost control of the mobile phone and the defendant completely obtained the absolute and exclusive possession of the mobile phone. Therefore, the defendant's unprepared escape behavior should be taken as the basis for determining his charges.

In this case, after the defendant obtained the victim's mobile phone by telephone, he did not immediately, absolutely and exclusively obtain the property during the telephone conversation. Because in this process, the victim has been around, that is, the victim has not lost control of the mobile phone, in other words, the defendant has not obtained property. After that, the defendant suddenly fled the scene unexpectedly, and the victim found it but could not recover it. At this point, the defendant obtained the property. The defendant's way of obtaining property is an act of fleeing while others are unprepared, that is, openly robbing others of property, which is one of the objective manifestations of robbery.

In summary, the defendant in this case should be convicted and punished for robbery.