Multiplex communications – Diagnostic testing – Determination of communication parameters
Reexamination Certificate
1999-02-18
2003-04-22
Marcelo, Melvin (Department: 2733)
Multiplex communications
Diagnostic testing
Determination of communication parameters
C370S255000, C370S524000
Reexamination Certificate
active
06553001
ABSTRACT:
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to a technique, particularly apparatus and accompanying methods, for inclusion within, e.g., ISDN DTE, and use in conjunction with an ISDN terminal adapter for automatically, rapidly and transparently providing ISDN switch detection and SPID configuration, and which specifically and advantageously expedites ISDN configuration of DTE and decreases long-term support costs of the adapter.
2. Description of the Prior Art
In recent years, a number of domestic and foreign telephone companies have begun offering integrated service digital network (ISDN) services to their customers. ISDN provides an integrated voice and data network that offers both increased bandwidth and significant flexibility over traditional analog telephone services. Inasmuch as subscriber charges for ISDN access are decreasing—with the decrease being rather noticeable for some telephone companies, demand for ISDN service and equipment is rising appreciably. Demand is particularly strong and growing for those subscribers who seek cost-effective high speed access to the Internet.
In particular, a basic rate (BRI—so-called “2B+D” service) ISDN interface provides higher speed bandwidth than both traditional analog, modem-based dial-up access modalities and comparably priced switched digital services. Each so-called B (“bearer”) channel, which carries subscriber voice and/or data, provides 64 Kbits/second of bandwidth; while a D (“data”) channel, which carries signaling and control information, provides 16 Kbits/second of bandwidth. For the bandwidth delivered, an ISDN line is significantly less expensive than a private leased line that supplies the same bandwidth. Furthermore, ISDN, being a digital end-to-end service, provides digital transmission channels that tend to be more accurate and reliable, from the standpoint of error rates and dropped connections, than are conventional analog connections. In addition, ISDN service provides rapid connect times which, in turn, provide faster support for those LAN (local area network) protocols that require relatively short latency across WAN (wide area network) connections.
Starting a few years ago, various networking and communications equipment manufacturers have been offering relatively inexpensive ISDN terminal adapters for subscriber end-use. Such a terminal adapter, also generically referred to as “data circuit terminating equipment” (DCE), once connected to an ISDN connection and to a subscriber's personal computer (PC), permits that subscriber to connect his(her) computer to, e.g., an Internet service provider and communicate at speeds approximately two to four times greater than a conventional analog modem. The computer so connected becomes so-called “data terminal equipment” (DTE). While the availability of these terminal adapters is clearly not the sole cause underlying the growth in ISDN usage, it, when combined with decreasing rates for ISDN service, is certainly a large and growing factor.
Ideally, an ISDN terminal adapter should be as easy for a subscriber to install and use as is a conventional analog modem. However, in practice, installing a conventional ISDN terminal adapter can be rather tedious, frustrating and time consuming. Many of these difficulties relate to a need for a user to manually supply the DTE, during its ISDN configuration, with a proper “SPID” (service profile identifier) for each different ISDN directory number (for each different B-channel) that has been assigned to the DTE. In that regard and with most ISDN switches, each different DTE that is to be connected to an ISDN switch needs to be electronically identified to that switch by the SPID(s) assigned to it by a local telephone company. While a connection is being established between the DTE, via the DCE, and the switch, the DTE will send, to the switch and for each different B-channel it desires to use, an initialization message containing a SPID, entered by the user, for that particular channel. In response, the switch will establish a connection, with the DTE but only through the B-channel(s) that has a correct SPID. If the user configures the DTE with an incorrect SPID, then all attempts by the DTE to establish a connection, via the DCE, to the switch and over the B-channel associated with the incorrect SPID will invariably fail.
In particular, SPID formats unfortunately vary across the United States. Furthermore, given the length of a SPID, a subscriber often incorrectly enters a SPID into a terminal adapter during its configuration. Also, local telephone company personnel frequently, though inadvertently, supply a subscriber with an incorrect SPID that differs from that which has been programmed, for that subscriber, into a local ISDN switch.
As to varying SPID formats, for the most part, ISDN service is quite uniform across the entire United States and Canada; however, slight differences do exist as to how ISDN service is implemented among various local telephone companies. In particular, a small number of ISDN switch manufacturers currently exists which supply such switches to local telephone companies in the United States. These manufacturers currently include Northern Telecom, Ltd., Siemens Corporation and. Lucent Technologies, Inc. Northern Telecom and Siemens currently offer one ISDN switch each (carrying product designations “DMS 100” and “EWSD”, respectively)—each being a so-called “NI-1” type (referring to “National ISDN 1”) switch and will be so referred to hereinafter. The Northern DMS 100 switch is available in two versions, i.e., an NI-1 version and a custom version—those versions differing only in their software. Lucent Technologies (previously a portion of AT&T) currently offers three different ISDN switches (a “5E Custom Multi-point”, “5E NI-1” and “5E Custom Point-to-point”), though all implemented on a common 5ESS hardware platform (these switches differing in their generics, i.e., software). While these switches are generally compatible with each other, idiosyncratic differences, including differences in SPID format, do exist among the these switches. These differences complicate installation and use of an ISDN terminal adapter. A SPID in one format, hence suited for use with one type of ISDN switch, may not function with another type of ISDN switch; thus, completely preventing any ISDN calls from being established through the latter switch. Therefore, while configuring the adapter, a user must obtain SPIDs from his(her) local telephone company in the specific format for the local ISDN switch that will serve that user.
While configuring conventional ISDN terminal adapters for use with an ISDN line, an ISDN subscriber is usually required to manually enter SPIDs provided by his(her) telephone company for that line into the terminal adapter. Depending on the terminal adapter and the interconnected terminal equipment, the SPIDs may be programmed either into the adapter or the terminal equipment (DTE) itself. In any event, a significant probability exists that the subscriber will enter such a SPID incorrectly or that one of the SPID(s) (s)he receives will itself be incorrect. As to the latter, when an ISDN line is ordered from a local telephone company, then, to provision the service, SPIDs are established for that line and then generally entered manually, as data, by telephone company personnel into a database, accessible by the ISDN switch. The local telephone company then notifies the subscriber of his(her) SPIDs. However, given the length of a SPID and similarity of some of its digits, an individual at the telephone company can inadvertently transcribe a SPID incorrectly from that which was just assigned and thus provide the subscriber with an incorrect SPID.
Hence, it is the subscriber, during installing his(her) ISDN terminal adapter, who often experiences first-hand the effect of an incorrect SPID. Since the vast majority of subscribers have no knowledge of ISDN control messages, let alone the particular type of local ISDN switch to which (s)he is to connect and the corr
3Com Corporation
Marcelo Melvin
Michaelson Peter L.
Michaelson & Wallace
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