ISDN IP CPE Using SCTP
Original Publication Date: 2004-Jun-25
Included in the Prior Art Database: 2004-Jun-25
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In the US telephony market, there are currently subscribers with ISDN phone sets, called herein as the TDM ISDN phone sets (TDM: Time Division Multiplexing; ISDN: Integrated Services Digital Network). These phone sets (also: Customer Premises Equipment, CPE) and the telephone switches follow the ISDN requirements being defined by e.g. special companies. The ISDN requirements, which are implemented in the phone set and the telephone switches, provide numerous features that the typical analog phone set does not provide. The method of connectivity prior to the evolution of the IP network (Internet Protocol network) is a physical direct connection to the ISDN line equipment contained in the telephone switch. With the advent of IP networks, access devices have been designed which contain the physical direct connection of the ISDN phone set on the side of the access device. Thereby the ISDN signaling messages to the telephone switch are sent over the IP network via the existing Stream Control Transmission Protocol (SCTP). In this configuration, the same TDM ISDN phone set prior to the IP evolution can still be used when connected to the access device of an IP network. By this means direct connectivity to the IP network is not provided, such as a Session Initiation Protocol (SIP) phone set or a phone set using the H.323 protocol. SIP and the H.323 protocol support a minor feature set than the TDM ISDN phone set.