Abstract: Buffer memory overflow control is realized by controlling the amount of packet data being inputted to the buffer memory in response to the amount of packet data stored in the buffer memory. Depending on the type of coding being employed and the amount of data stored in the buffer memory, one or more groups of bits are controllably dropped from the packet information field being inputted into the buffer memory.

Abstract: Delay that a packet experiences in a network node is measured by employing a single local time signal in the node, and by separating a time stamp update function into a network node entry stamp function and a network node exit time stamp function. The node entry time stamp function is to generate a packet originate time value referenced to the local time signal value upon the packet entering the node. This packet originate time value is inserted into a packet header time stamp field to be transported through the node. The node exit time stamp function is to generate an updated time stamp value from the packet originate time value from the header time stamp field and the local time signal value upon the packet exiting the node. The undated time stamp value is inserted into the packet header time stamp field in place of the packet originate time value.

Abstract: Unwanted distortion in signals being reconstructed from packets is substantially eliminated by employing a virtual sequence packet numbering scheme in conjunction with a time stamp value. A virtual sequence number which accompanies the packet identifies the location of the packet in an information spurt. If the packet is the initial packet in the information spurt, the time stamp value is used to "build out" the delay experienced by the packet to a fixed overall value. Subsequent packets in the information spurt are concatenated to the information spurt. A packet following one or more lost packets is also identified by the packet virual sequence number and is also treated as an initial packet.

Abstract: In a speech signal being reconstructed from digital samples, artificial gaps caused by discarded late packets are minimized by holding state varibales constant in a decoder used to reconstruct the speech signal. The decoder state variables are held constant from the end of the last previous packet information field for up to a prescribed interval. Upon arrival of the "late" packet, the decoder passes from the hold variables state to its normal operating state and reading out of samples from the packet information field is initiated immediately. Subsequent packets in the information spurt are concatenated to the late arriving packet.

Abstract: A packet information field format is disclosed which facilitates packet buffer memory overflow control. Generation of the information field is such that like bits from samples representing a corresponding communication channel from a plurality of frames are grouped together. In a specific embodiment, the bits from the communication channel samples are arranged in groups including the most significant bits to the least significant bits. The packet header also includes a field which can have an indication therein of whether bits can be dropped from the packet and an indication of whether bits have already been dropped from the packet. Consequently, dropping of bits from the packet is readily achieved by first dropping the group including the least significant bits, then dropping the group including the next to least significant bits, if necessary, and so on until it is determined that the entire packet should be dropped, if necessary.