Abstract: In a communication system pursuant to the frame relay (FR) architecture, to prevent disability of a data transmission due to the discarding of LMI data. When receiving FR frames from an FR terminal 16, a multiplexer 14-2 separates LMI frames stored with LMI data from user frames stored with user frames, based on values of DLCI address fields, and queues them separately. The multiplexer 14-2 sends all of the queued LMI frames via the data transmission path 18 in a preferential manner and, then, it sends a portion of the queued user frames that is transmissible by a remaining portion of the transmission capacity to the data transmission path 18, thereby causing the user frames alone to be subjected to shaping processing.

Abstract: Systems and methods are provided for effectively using a trunk line in a speech compression system by dynamically selecting or changing the trunk line based on a band use rate. Then the line usage is equal to or greater than a threshold value, a currently connected call is switched to a compression method which requires less bandwidth. A switch enabling attribute is set for each can and a switch enabled call is selected as a target for switching and a transmission side and a reception side acquire the resources that are needed for use of compression after switching. When the acquisition of the resources is successful, a data transfer is performed for the currently connected resources and the newly acquired resources. After the data transfer, both resources are synchronized and the resource that was used by the call are released.