Abstract: The present invention provides for improved security in a VoIP architecture. In accordance with an embodiment of the invention, a system for providing VoIP service to a user domain having user accessible equipment includes a first domain having VoIP service provider equipment and a second domain having at least one border element communicating with the service provider equipment and the user accessible equipment to enable communications between the service provider equipment and the user accessible equipment. The user accessible equipment is prevented from directly communicating with the service provider equipment.

Abstract: A frame layer communications system for packet-switched virtual circuits that provides error detection when the link layer both corrupts and discards cells. An illustrative embodiment of the invention provides two error detection mechanisms: the first for the user-data and the second for certain control information. When the frame is segmented into cells, the control information and information relating to the second error detection mechanism are segmented into a single cell.

Abstract: A universal protocol data receiver is disclosed which is capable of receiving data streams in character mode and block mode, providing flow control and error detection and correction. The receiver is divided into two stages separated by a first-in, first-out buffer register. The first stage handles flow control and error processing as well as initialization. The second stage handles interfacing with the data utilizing mechanism and flow control acknowledgements. The FIFO buffer is divided into two parts by a movable barrier which limits the access of the second stage. The barrier permits error processing by hiding incoming blocks of data behind the barrier until processing is complete. Both a hardware and a software implementation of the receiver are disclosed.