METHOD AND APPARATUS FOR TRANSFERRING A DATA CALL THROUGH A PBX

Abstract: The operating logic of a first communication interface device (124*), a callee, is enhanced to include logic for transferring a direct inward dial data call it received from a second communication interface device (124*), the caller, to a compatibly equipped third communication interface device (124*), the transferee, coupled to the same PBX (18). The operating logic of the second and third communication interface devices, the original caller and the transferee, are also enhanced to include logic for cooperating with the first communication interface device to effectuate the transfer. Preferably, the operating logic of first, second, and third communication interface devices are further enhanced with the enhancements provided to the second and third, first and third, and first and second communication interface devices respectively, to allow each of the three communication interface devices to be the caller having its call transferred, the transferor callee, as well as the transferee callee, at different points in time.

Description: Method And Apparatus For Transferring A Data Call Through A PBX BACKGROUND OF THE INVENTION 1 . Field of the Invention The present invention relates to the field of data communication. More specifically, the present invention relates to communication interface devices, including data circuit-terminating equipment (DCE), also known as modem. Background Information As computer and telecommunication technologies continue to advance, more and more data processing equipment are equipped with communication interface devices, from conventional DCEs to simultaneous voice and data (SVD) modems for POTS connections, to ISDN based interface devices, for the purpose of conducting data communication and/or audio and video exchanges over the different transport types. In this context, the data processing equipment are also referred to as data transmitting equipment (DTE). Typically, two communication interface devices interconnect two DTEs together by jointly establishing a connection in accordance with a data communication protocol, which usually dictates among other things the transmission of a carrier signal. Failure to receive this carrier signal from the other side in the prescribed time frame is construed by most interface devices as the loss of connection. In addition, depending on the sophistication of the protocol, the two interface devices might have jointly established a data transmission rate, a data blocking factor, whether the data will be exchanged with or without error correcting, and/or compression decompression, and the compression/decompression technique etc. Today, by virtue of the direct inward dialing capability of modern private access branch exchanges (PBX), a DTE, through its communicatior interface device can actually initiate data communication with another DTE, having a compatible communication interface device, located "behind" the PBX, by calling the compatible communication interface device directly. However, because the carrier signal is typically required in a much shoπer time than the time it takes a PBX to transfer a call, unlike a direct inward dial voice call, the callee DTE cannot cause its communication interface device to transfer the call to yet another DTE also having a compat bly equipped communication interface device connected to the same PBX. Experience has shown that for many modern data and/or voi:e applications, it is desirable to be able to transfer such a direct inward dial da a. call from one callee DTE to another DTE, having a compatibly equipped commi nication interface device connected to the same PBX. As will be disclosed in more cetail below, the present invention achieves this and other desirable results. SUMMARY OF THE INVENTION The operating logic of a first communication interface device , a callee, is enhanced to include logic for transferring a direct inward dial data call it received from a second communication interface device, the caller, through a PBX, to a compatibly equipped third communication interface device, the transferee, coupled to the same PBX. T e operating logic of the second and the third communication interface devices, the original caller and the transferee, are also enhanced to include logic for cooperating with the fust communication interface device to effectuate the transfer. More specifically, for the purpose of enabling the second communication interface device, the caller, to accommodate having the direct inward dial data call it initiated to be transferred, its operating logic, is enhanced to temporarily suspend looking for the carrier signal from the callee, upon beirg informed that the call is being transferred, if the second communication interface device is a modem. On the other hand, if the second communication interface is an Integrated Service Data Network (ISDN) compliant interface instead, its operating logic is enhanced to temporarily suspend looking for the frame alignment signal from the callee. The operatic logic of the second communication interface device, the caller, is also enhanced to initiate a retraining procedure, when it resumes looking for the carrier/frame alignment signal from the callee, if the second communication interface device, the caller, was also informed to assume loss of protocol when looking for the carrier/frame alignment signal from the callee. Additionally, for the purpose of enabling the first communication interface device, the transferor callee, to be able to transfer the direct inward dial data call it receives, its operating logic is enhanced to inform the second communication interface device, the caller, of the transfer, with or without informing it to assume loss of protocol when it resumes looking for the carrier/frame alignment signal from the callee, depending on whether the "host" DTE of the first communication interface device, the transferor callee, has an alternate connection to the "host" DTE of the desired transferee. The operating logic of the first communication interface device, the transferor callee, is also enhanced to inform it's "host" DTE of the operating parameters for handling the data call, thereby allowing the information to be provided to the "host" DTE of the third communication interface device, the transferee callee, if the two "host" DTEs have an alternate connection. Lastly, the operating logic of the first communication interface device, the transferor callee, is further enhanced to inform the PBX of the identity of the transferee. Furthermore, for the purpose of allowing the third communication interface device, the transferee callee, to be able to accept a transferred call, its initialization logic is enhanced to initialize itself to a particular set of operating parameters, under the control of its "host" DTE. The initialization logic of the third communication interface device, the transferee callee, is also enhanced to skip the "standard" handshake and negotiations for establishing these operating parameters if it has so initialized itself prior to answering a call. Lastly, the operating logic of the first, second, and third communication interface devices are preferably further enhanced with the enhancements provided to the second and third, first and third, and first and second communication interface devices respectively, to allow each of the three communication interface devices to be the caller having its call transferred, the transferor callee, as well as the transferee callee, at different points in time. BRIEF DESCRIPTION OF DRAWINGS The present invention will be described by way of exemplar/ embodiments, but not limitations, illustrated in the accompanying drawings in which like references denote similar elements, and in which: Figure 1 illustrates an exemplary network of DTEs incorporated with the teaching of the present invention; Figure 2 illustrates one embodiment of a DTE of Figure I ; Figures 3a - 3c illustrate three embodiments of the communication interface device of Figure 2; and Figures 4a - 4c illustrate one embodiment each of the improved operational flow of the caller, callee (transferor) and the transferee communication interface devices. DETAILED DESCRIPTION OF THE INVENTION In the following description, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art at the present invention may be practiced without the specific detail >. In other instances, well known features are omitted or simplified in order not to obscure the present invention. Furthermore, for ease of understanding, some method steps are described as separate steps, however, it should not be construed that these steps are necessarily order dependent. Referring now to Figure 1, wherein an exemplary network of DTEs is shown incorporated with the teachings of the present invention. As shown, the exemplary network of DTEs include DTEs 12, 14 and 16. DTE 14 and DTE 16 are coupled to PBX 18. Additionally, for the illustrated embodiment, DTEs 14 and 16 are coupled to an alternate connection, shown here as local area network (LAN) 20. DTE 12 conducts data communication with DTE 14 or DTE 16 through a public switching network 22 and PBX 18. Public switching network 22 may be a general switching telephone network (GSTN) or ISDN or the like, depending on the type of communication interface devices included in DTEs 12, 14 and 16. The communication interface devices may be analog or SVD modems, in which case, public switching network 22 would be GSTN. In other words, the connection between DTE 12 to DTE 14 or 16 is a POTS connection. On the other hand, if the communication interface devices are ISDN based, public switching network 22 would be ISDN. The connection between DTE 12 to DTE 14 or 16 is an ISDN connection. Figure 2 illustrates an exemplary embodiment of DTE 12, 14 and 16 of Fig. 1. As shown, DTE 12, 14 or 16 includes processor 102, cache 104, memory 106, memory controller 108 and processor bus 110 coupled to each other as illustrated. Furthermore, DTE 12, 14, or 16 includes I/O controller 112 coupled to a standard I/O bus 126 and to a high-speed I/O bus 118. Coupled to standard I O bus 126 are mass storage 120, keyboard 122 (including a cursor control device such as a mouse), and communication interface device 124. Coupled to high speed I/O bus 118 are video I/O devices 116 such as a display and/or a camera, and audio I/O device 114 such as a microphone and speakers. SUBSTTTUTE SHEET (RULE 26) Communication interface device 124 is incorporated with the teachings of the present invention, to be more fully described below. Other elements perform their conventional functions, whose constitutions are well known and will not be further described. Based on the description to follow, a person skilled in the art will appreciate that the present invention may be practiced without some of the illustrated elements or with other additional elements. The illustrated embodiment is intended to represent a broad category of DTEs known in the art including but not limit<ϊd to personal computer systems based on Intel® Architecture Processors. Additionally, it should also be noted that while communication interface device 124 is being shown as an independent device "internal" to the host DTE, the present invention may also be practiced on independent communication interface devices that are extemal io the DTEs. Nevertheless, for ease of explanation, the coupled DTE shall still be referred to as the "host" DTE. Furthermore, it is anticipated that the present invention can also be practiced on "compound function devices" such as an I O controller having integrated communication interface functions, as the technology of integration continues to advance. Figures 3a - 3c illustrate three exemplary embodiments ol the communication interface device shown in Fig. 2. Communication interfac device 124a of Fig. 3a is intended to represent a broad category of conventional inalog modems, each having an UART interface 152 to the rest of the "host" DTE, microcontroller 154 for controlling the overall operation of the device, data pump 156 for sending and receiving data, and DAA 158 for actually placing the data as electrical signals onto line 160. Communication interface device 124b of Fig, 3b is intended to represent a broad category of SVD modems, each having, in addition to UART 152, microcontroller 154, data pump 156 and DAA 158, a block transfer interface 162 for transferring digitized voice signals to and from the "host" DTE, integrated voice compression/decompression circuitry 164 for compressing and decompressing digitized voice signals, and a start tone detector 166 for providing certain voice and/or SUBSTTTUTE SHEET (RULE 26) data operation control signals to microcontroller 154. Voice and data are multiplexed under the control of microcontroller 154. Communication interface device 124c of Fig. 3c is intended to represent a broad category of ISDN based communication interface devices, each having, in addition to microcontroller 154, first block transfer interface 162a (for transferring voice), voice compression/decompression circuitry 164, two additional block transfer interfaces 162b and 162c for transferring video and data (including commands) respectively, and video CODEC 168 for encoding and decoding video signals. Voice and Video/Data are also multiplexed under the control of microcontroller 154. In each case, microcontroller 154 is incoφorated with initialization and operating logic for operating the communication interface device 124a - 124c in a manner that's suitable for the type of connection(s) supported, which includes the initialization and operating logic for jointly establishing a connection and data communication protocol. Particular examples of data communication protocol includes ITU's V.42 for a POTS connection and V.120 for an ISDN connection. Furthermore, the initialization and operating logic are incorporated with the teachings of the present invention for supporting transfer of a direct inward dial data call through a PBX, to be described more fully below. Except for these teachings of the present invention, communication interface devices 124a - 124c are well known in the art, and will not be otherwise further described. Figures 4a - 4c illustrate the teachings of the present invention in the cases of a caller, a transferor callee, and a transferee callee, respectively. As shown in Fig. 4a, as in the prior art, as a caller, communication interface device 124a, 124b, or 124c (hereinafter 124*) initiates a direct inward dial data call to a callee communication interface device 124*, step 202. The two communication interface devices 124* jointly establish the connection including the data communication protocol in accordance with a protocol both of them support, e.g. ITU V.24 or V.120, step 204. Among other things, the two communication interface devices 124* joindy establish the data rate, whether error correction is going to be used, whether compression/decompression will be employed, and if so, the compression/decompression technique or character string etc. Upon establishing the connection and data communication protocol, the two communication interface devices 124* proceed to exchange data on behalf of their host DTEs 12 and 14. However, in accordance with the present invention, the operating logic of communication interface device 124* is enhanced, when acting as a caller, to detect notification from the callee that the direct inward dial data call is being transferred, step 206. In one embodiment, the notification includes whether the caller communication interface device 124* should assume loss of protocol when the transfer is completed, to be described more fully below. Such notification may be implemented in a variety of manners, e.g. via an XID frame if the call is conducted using one of ITU's V series protocols. If no such notification is detected, the operating logic proceeds as in the prior art, and eventually terminates the ca 1 if a termination condition is detected, step 216. On the other hand, if a transfer notification is detected at step 206, the operating logic is enhanced to temporarily suspend looking for the carrier signal from the callee if the caller communication interface device is a modem. On the other hand, if the caller communication interface device is an ISDN interface, the operating logic is enhanced to temporarily suspend looking for the frame alignment signal fron the callee. For the illustrated embodiment, the operating logic sets a timer for a predetermined amount of time, step 208. During this period, the operating logic stops detecting for the carrier/frame alignment signal from the callee, step ,10. Alternatively, the operating logic ignores the "prolonged" absence of the earner signal from the callee. At the end of the time period, the operating logic resumes looking fo: the carrier/frame alignment signal from the callee, step 212. If there's still no carrier/frame alignment signal from the callee, the operating logic terminate:, the call. If carrier/frame alignment signal from the callee is detected again and the communication interface device 124* was previously notified to assume loss of protocol, step 214, the operating logic initiates a retraining procedure, step 204, otherwise, the operating logic simply proceeds to operate as if the call has not been transferred. The amount of time caller communication interface device 124* temporarily suspends looking for the carrier/frame alignment signal from the callee should be sufficiently long to allow the call to be transferred through a PBX. The actual time value may be empirically determined. In one embodiment, it is set at 200 ms. As shown in Fig. 4 b, as in the prior art, as a callee, the operating logic accepts the direct inward dial data call, step 222. As described earlier, the two communication interface devices 124* jointly establish the connection and data communication protocol, step 224. Once the connection and the data communication protocol is established, the operating logic proceeds to operate as in the prior art. However, in accordance with the present invention, the operating logic is enhanced to detect an instruction from the "host" DTE to transfer the call to a transferee callee, step 226. In one embodiment, in addition to the transferee callee identification, the instruction also includes a request for the operating parameters of the call. The "host" DTE of transferor communication interface device 124* requests the operating parameters, if it has an alternate connection to the "host" DTE of the transferee communication interface device 124*. The instruction/request may be implemented in a variety of manners, using for example an escape sequence to distinguish the instruction/request from normal data traffic. If no such instruction/request was detected, the operating logic proceeds to operate communication interface device 124* as in the prior art, and eventually terminates the call if one of the termination conditions is detected, step 228. 10 On the other hand, if an instrucπon to transfer the call is detected at step 226, the operaung logic further determines if the "host" DTE has previously requested the operating parameters for the call, step 230. If the "host" DTE has not previously requested the operating parameters, the operating logic notifies the caller communication interface device 124* that the call is being transferred, and it should assume loss of protocol at the end of the transfer, step 236 If the "host" DTE has previously requested the operating parameters, the operating logic provιde:> the operating parameters to the "host" DTE, step 232. Then, the operating logic noufies the caller communication interface device 124* that the call is being transf ϊrred, but without telling the caller communication interface device 124* that it shou Id assume loss of protocol at the end of the transfer, step 234. In either case, upon notifying the caller communicauon interface device 124*, the transferor callee communicauon interface device 124* noufies the PBX to transfer the call to the transferee callee communicauon interface device 124* As shown in Fig. 4c, as in the pπor art, transferee communication interface device 124* responds to either commands from its "host" DTE or the πng signal, step 242. Upon receipt of a command, the operating logic determi les whether if the command is for lnmalizing the communication interface device 124* to a certain set of operating parameters, step 246. If the command is for such initializiuon, the operating logic lnmalizes the communication interface device 124* accordingly, step 250. The operating parameter set is provided by the "host" DTE, who received them from the "host" DTE of the transfemng communication interface device 124* If it is one of the conventional commands, then the operating logic handles the conventional command as in the pπor art, step 248. On the other hand, upon receipt of a πng, beside answeπng the call, step 252, the operating logic additionally determines if the communicauon interface device 124* has been previously initialized to a certain set of operating parameters in response to a request from the "host" DTE, step 254 If the communicauon interface device 124* has not been previously so lniuahzed, the operating logic proceeds to jointly establish the connection and data communication protocol as in the prior art, step 258. Upon establishing the data communication protocol, the operating logic proceeds to operate the communication interface device 124* also as in the prior an, until eventually a call termination condition is detected, and the operating logic terminates the call, step 256. However, if it was detected at step 254 that the communication interface device 124* has previously been initialized to certain set of operating parameters, in response to a request from the "host" DTE, the operating logic proceeds immediately to operate the communication interface device 124* without going through the "negotiation" steps, as if those steps had been performed. Similarly, the operating logic will operate communication interface device 124* until the call is terminated. For ease of understanding, the enhancement to the operating logic has been described separately in terms of the enhancements to allow the various communication interface devices to act as a caller, as a transferor callee, and as a transferee callee. Obviously, a communication interface device may be a caller at one point in time, a transferor callee at another time, and a transferee callee at yet another point in time. Therefore, communication interface device 124* is preferably provided with all three types of enhancements to allow communication interface device 124* to act in each of the three different roles at different points in time. Thus, a method and apparatus for transferring a data call through a PBX has been described. While the method and apparatus of the present invention has been described in terms of the above illustrated embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described. The present invention can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of restrictive on the present invention. SUBSTTTUTE SHEET (RULE 26)

Claims: CLAIMS What is claimed is: 1. An apparatus comprising improved operating logic for originating and conducting a data call with a callee coupled to a private branch exchange (PBX), through a communication connection, wherein the improvement includes logic for temporarily suspending monitoring for loss of said communication connection, in response to being informed by the callee that the data call is being transferred to a transferee coupled to the PBX. 2. The apparatus as set forth in claim 14, wherein the logic for tempoiarily suspending monitoring for loss of said communication connection comprises logic for temporarily suspending monitoring for a carrier signal. 3. The apparatus as set forth in claim 14, wherein the logic for tempoiarily suspending monitoring for loss of said communication connection comprises logic for temporarily suspending monitoring for a frame alignment signal. 4. The apparatus as set forth in Claim 14, wherein the improvement further includes logic for initiating a retraining procedure when monitoring for loss of said communication connection is resumed, if the apparatus was also informed by the callee to assume loss of protocol when resuming monitoring for loss of said communication connection. 5. The apparatus as set forth in claim 14, wherein the apparatus is a communication interface device. 6. The apparatus as set forth in claim 14, wherein the apparatus is a computer system. SUBS TTUTE SHEET (RULE 26) 7. The apparatus as set forth in claim 14, wherein the apparatus is a communication device. 8. An apparatus designed to be coupled to a private branch exchange (PBX), the apparatus comprising improved operating logic for receiving and conducting a data call with a caller, through a communication connection, wherein the improvement includes logic for informing the caller that the data call is being transferred to a transferee coupled to the PBX. 9. The apparatus as set forth in claim 21, wherein the improvement further includes logic for instructing the PBX to transfer the data call to the transferee. 10. The apparatus as set forth in claim 21, wherein the improvement further includes logic for transferring a plurality of operating parameters to the transferee, over another communication connection that by-passes the PBX, for use by the transferee to conduct the data call with the caller. 11. The apparatus as set forth in claim 21 , wherein the apparatus is a communication interface device. 12. The apparatus as set forth in claim 21, wherein the apparatus is a computer system. 13. The apparatus as set forth in claim 21, wherein the apparatus is a communication device. 14. An apparatus designed to be coupled to a private branch exchange (PBX), the apparatus comprising improved operating logic for receiving and conducting a data call with a caller, over a communication connection, the improvement including logic for skipping a number of set up steps for establishing a plurality of operating parameters for conducting the data call, when answering the data call, if the operating parameters have been pre-established in preparation for transfer of the data call from a transferor coupled to the PBX. 15. The apparatus as set forth in claim 27, wherein the improvement further includes logic for accepting the plurality of operating parameters from the iransferor, over another communication connection that by-passes the PBX, and in response, pre-establishing the operating parameters in preparation for transfer of the data call from the transferor. 16. The apparatus as set forth in claim 27, wherein the apparatus is a communication interface device. 17. The apparatus as set forth in claim 27, wherein d e apparatus is a computer system. 18. The apparatus as set forth in claim 27, wherein the apparatus is a communication device. 19. A method for a caller to accommodate transfer of a data call original ed by the caller, from a callee coupled to a private branch exchange (PBX) to a transf eree coupled to the PBX, the method comprising the steps of: (a) receiving notification from the callee that the data call is being transferred from the callee to the transferee; and (b) in response, temporarily suspending monitoring for loss of communication connection. 20. The method as set forth in claim 32, wherein step (b) comprises temporarily suspending monitoring for a carrier signal. 21. The method as set forth in claim 32, wherein step (b) comprises temporarily suspending monitoring for a frame alignment signal. 22. The method as set forth in claim 32, wherein the method further comprises step (c) initiating a retraining procedure when resuming monitoring for loss of communication connection. 23. A method for a callee coupled to a private branch exchange (PBX) to transfer a data call to a transferee coupled to the PBX, the method comprising the steps of: (a) providing a call transfer notification to an originating caller of the data call that results in temporary suspension of monitoring by the originating caller for loss of communication connection; and (b) instructing the PBX to transfer the data call to the transferee, to be accomplished during the temporary suspension. 24. The method as set forth in claim 36, wherein step (b) further comprises providing a plurality of operating parameters to the transferee, through a communication connection that by-passes the PBX, prior to performing said instructing. 25. A method for a transferee coupled to a private branch exchange (PBX) to accept transfer of a data call from a callee coupled to the PBX, the method comprising the steps of: (a) answering the data call; (b) determining if a plurality of operating parameters have been pre-established in anticipation of the data call being transferred from the callee; and (c) skipping a number of set up steps for establishing the operating parameters if the operating parameters have been pre-established. 26. The method as set forth in claim 38, wherein step (a) further comprises accepting the plurality of operating parameters from the callee, and pre-establishing the operating parameters in preparation for transfer of the data call from the callee, prior to answering the data call. SUBSTTTUTE SHEET (RULE 26)

Inventors: KISOR GREGORY H, PENDSE AJIT, KISOR, GREGORY, H., PENDSE, AJIT
Applicants: INTEL CORP, KISOR GREGORY H, PENDSE AJIT, INTEL CORPORATION, KISOR, GREGORY, H., PENDSE, AJIT
Application year: 1996
Main classification: H04M11
IPC codes: H04L12, H04M3, H04M11, H04Q3