Communication method and apparatus, and communication system

A communication apparatus, comprising:

• at least one processor, wherein the at least one processor is coupled to a non-transitory memory,
• the non-transitory memory stores a computer program, that when executed by the at least one processor, causes the apparatus to perform operations including:
• receiving session description protocol (SDP) offer information, wherein the SDP offer information indicates that a second communication entity offers to use a first-type protocol stack or a second-type protocol stack to establish a data channel, the data channel is associated with an internet protocol multimedia subsystem (IMS) session between a first communication entity and the second communication entity, the first-type protocol stack corresponds to a datagram transport layer security (DTLS) protocol, and the second-type protocol stack does not correspond to the DTLS protocol;
• and
• sending SDP answer information based on the SDP offer information, wherein the SDP answer information indicates that the first communication entity determines to use the second-type protocol stack to establish the data channel.