Multiplex communications – Network configuration determination
Reexamination Certificate
1998-03-17
2001-06-12
Chin, Wellington (Department: 2664)
Multiplex communications
Network configuration determination
C370S463000, C370S465000, C370S524000, C709S228000, C710S068000
Reexamination Certificate
active
06246671
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a link pre-establishment control mechanism employed by the microcontroller of integrated services digital network (ISDN) terminal equipment. In particular, the invention is directed to an automated telecommunication switch type and protocol detection (or AUTOSWITCH) routine, which interrogates the telecommunication switch of a local service provider with a message, that causes the switch to transmit a response message, from which both the type and communication protocol of the switch can be readily determined. Once determined, this switch type and protocol information may be used by the automated service profile identifiers (SPID) detection mechanism described in the above-referenced '241 patent to facilitate SPID generation.
BACKGROUND OF THE INVENTION
As described in the above-referenced '241 patent, integrated services digital network (ISDN) communications make it possible for telephone service providers to supply multiple types of signalling channels from a central office over a single twisted pair-configured, local loop to a network termination interface or ISDN terminal equipment. Such ISDN equipment may comprise, but is not limited to, an ISDN phone, an X.25 packet device, or an ISDN terminal adapter, to which customer premises-resident data terminal equipment may be coupled. These multiple types of signalling channels typically include a digital data channel, a digitized voice channel and a separate dialing channel.
In order for a customer to place a call through an installed piece of terminal equipment, it is necessary that the terminal equipment's supervisory communication controller be properly preconfigured with a prescribed set of communication parameters. These parameters include the telecommunication switch protocol employed in the local service provider's central office facility, the local directory numbers (LDNs), including area codes, associated with the two ISDN bearer (B1, B2) channels, and a service profile identifier or SPID. (The SPID is a sequence of digits, which identifies the ISDN terminal equipment that is coupled to the ISDN switch, and is assigned by the local telephone service provider, when the ISDN line is installed.)
Now even though the switch protocol and SPID parameters are routinely supplied by the telephone service provider to the purchaser of the ISDN terminal equipment, the end user is unfamiliar with ISDN terminology, and is accustomed to simply installing an analog modem in the customer's premises-located equipment, and plugging a telephone connector into a modem port (such as an RJ 11 jack). Indeed, experience has shown that on the order of eighty percent of ISDN customers will burden the equipment supplier and/or the local telephone service provider with requests for technical support, in the course of configuring the settings for ISDN terminal equipment, even if the service provider has correctly supplied the customer with each of the switch protocol, SPID and LDN parameters for use by the customer's ISDN terminal equipment.
Advantageously, the invention described in the '241 patent successfully remedies this problem by means of an automated SPID/switch detector mechanism (or AUTOSPID detector), that is incorporated into the terminal equipment's communication control software. The only customer participation required is that of inputting the local directory numbers (including area code), and invoking the AUTOSPID mechanism via a user interface. Once invoked, the AUTOSPID mechanism proceeds to automatically step through a prescribed SPID table search and generation sequence, followed by placing a test call communication exchange with the telecommunication switch employed by the local service provider to couple the customer's equipment with the network.
Now although the AUTOSPID detection scheme described in the '241 patent is a very effective mechanism for remedying the above-referenced terminal equipment configuration problem, it would be desirable to enhance (e.g., improve the reliability of) that AUTOSPID detection scheme, on the one hand, and to provide, in addition, a mechanism that is able to determine, independently of SPID generation, both the type and communication protocol of the telecommunication switch to which the customer's ISDN terminal adapter is coupled.
SUMMARY OF THE INVENTION
In accordance with the present invention, this objective is attained by means of an automated telecommunication switch type and protocol detection routine, termed AUTOSWITCH, which is operative to interrogate the telecommunication switch with a prescribed switch-interrogation message. The content of this interrogation message has been composed, so that it is insufficient to be recognized by the switch as a fully valid message, yet is sufficient to evoke a reply from the switch, which uniquely identifies both the type and the protocol being used by the switch, regardless of switch type. Once switch type and protocol have been automatically determined, this information may be coupled with the automated service profile identifiers (SPID) detection mechanism described in the above-referenced '241 patent to facilitate generation of the requisite SPID(s).
The switch-interrogation message employed in the present invention includes a standard header portion which conforms with conventional switch communication protocol. Following the header is a byte having the value 7b (hex), an information message type, which includes a first byte having the value 1c, a facility information element, followed by a byte representative of the length of the facility information element. This is followed by a service discriminator byte, which, in turn, is followed by the components of the facility information element, comprised of a payload sequence of arbitrary bytes. In order to prevent the switch from understanding the interrogation message, an invalid value is inserted in the location of the service discriminator; also, the payload component of the facility information element an invalid sequence (an alternately repeating series).
Once the terminal adapter has assembled the switch-interrogation message it transmits the message to the switch and waits for a reply message. The contents of the switch response message can be expected to correspond to one of those listed in a table associated with currently employed switches, so that a comparison of the contents of the response message from the switch with the various tabulated response messages will allow the switch protocol to be identified. Once a reply message from the interrogated switch is received, the process proceeds to sequence through respective query steps, associated with the respectively different switches and protocols of the table, to identify the switch protocol and switch type.
If any of the query steps successfully identifies the switch type and protocol, the process conveys that information to the AUTOSPID routine described in the '241 patent, which is then run to completion, using the identified switch protocol information to facilitate the automatic SPID generation. If the switch type and protocol are not identified, however, then it is inferred that the switch protocol is none of those listed in the table, and the routine branches to the AUTOSPID routine of the '241 patent, but without switch protocol information.
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Glass, III James M.
Lattanzi Michael T.
McElroy Paul G.
Rehage Charles R.
Adtran Inc.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Chin Wellington
Tran Malkhanh
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