Abstract: The architecture of a stackable VoIP telecommunication application system is proposed; and the firmware implementation of the VoIP card based on the IP stackable-oriented attribute is described emphatically. A VoIP card can support 8 voice channels, and the cards can be independently connected with each other through IP by the self-defined communication protocol，the stackable attribute based on IP is realized. This protocol is used to implement the communications among the channels within the voice-chip, among voice-chips within the card, among different VoIP cards, between the VoIP cards and the management PC. To improve the real-time capability, the control software of the VoIP card is running under the kernel module model, and the call-back function is triggered by the interruption service routines of VINETIC-2CPE voice-chip under the kernel module model.