Abstract: A system and method for a Universal Serial Bus (USB) device supporting both PSTN and DECT external interfaces. A USB device has distinct and dedicated external interfaces for providing multi-functionality capabilities. The host PC coordinates device interfacing through separate interface drivers associated with the USB device external interfaces. Future replacement of either external interface functionality is allowed without effecting the host PC driver or firmware architecture.

Abstract: Improved methods and arrangements are provided for supporting multiple simultaneous isochronous data transfers in a stream pipe of a Universal Serial Bus (USB). The stream pipe is subdivided into a plurality of channels. Devices requiring isochronous data transfers over the USB are dynamically assigned to use a particular channel as defined and mapped using a channel assignment message. In this manner, a plurality isochronous data transfers can be accomplished simultaneously within a single stream pipe. The improved methods and arrangements can be advantageously applied to computer telephony systems that need to support a plurality of user access devices and/or connect to multiple external telephone lines.