An information transmission method is provided. An apparatus receives a first session request from a third party application function, which includes identity information of the third party application function and identity information of a destination entity in a network. The apparatus establishes a first session with the third party application function; sends a second session request to the destination entity, which includes identity information of an anchor entity and the identity information of the third party application function. The apparatus establishes a second session with the destination entity; receives information reported by the destination entity, which includes a report event and identity information of the third party application function. The apparatus forwards the report event to the corresponding third party application function according to the identity information of the third party application function included in the information. Correct identification and forwarding of a packet flow is achieved.