the present invention relates to the communication field and discloses a communication method and gateway device based on session initiation protocol phones . to enable a sip phone to communicate over the circuit switched domain of a high speed packet access network , the technical solution of the present invention includes : when receiving sip signaling from a sip phone , sending an hspa call command associated with the sip signaling to an hspa network device ; when receiving an hspa call command from the hspa network device , sending sip signaling associated with the hspa call command to the sip phone ; when receiving a real - time transport packet from the sip phone , sending pulse code modulation data associated with the rtp packet to the hspa network device ; and when receiving pcm data from the hspa network device , sending an rtp packet associated with the pcm data to the sip phone . the present invention is applicable to sip communications .