Session Initiation Protocol (SIP) is a call control signaling protocol for Internet Protocol (IP) networks. SIP is designed to be device-agnostic—that is, it is intended to provide a highly flexible call signaling capability that is not tailored to the capabilities of any particular device. Analog telephone signaling, on the other hand, is device-specific and highly constrained because of the historical legacy of the services delivered to the device. As a result, many call features available in traditional analog telephone devices are not easily integrated in a SIP-based network.
In order to facilitate a fuller understanding of the exemplary embodiments of the present inventions, reference is now made to the appended drawings. These drawings should not be construed as limiting, but are intended to be exemplary only.
A system and process of an exemplary embodiment of the present invention provides a SIP-based call parking service by replicating the behavior of call parking in a public switched telephone network (PSTN). An embodiment of the present invention allows a caller to put an active call in a “parked” state by performing a hook flash (e.g., a quick hang-up and pick-up or other action) followed by entering a parking code and an optional destination code. The parked call may be retrieved by going off-hook (e.g., picking up) and entering the parking code and destination code (if one was entered). In one embodiment of the present invention, a notification signal (e.g., a ring, etc.) may be provided if the parked call remains parked for an extended duration of time.
SIP Device 110 may represent a device that manages User Interface 114. User Interface 114 may include a traditional telephone and other data communication device using voiceband or other signaling, including but not limited to data modems, facsimile devices, teletype (TTY) equipment, etc. SIP Device 110 may contain SIP User Agent 112. SIP User Agent 112 may be integrated with SIP Device 110 or remote from SIP Device 110. SIP User Agent 112 may perform interworking between SIP signaling and user interface actions. For example, SIP User Agent 112 may manage an exchange of media (e.g., audio, etc.) between User Interface 114 and a Real Time Protocol (RTP) media stream of a media session set up by the SIP signaling. SIP Device 110 may originate calls to and receive calls from other users. SIP Device 110 may communicate through IP Network 120 to SIP Server 122.
SIP Server 122 may represent a SIP proxy or application server that acts on behalf of SIP Device 110. For example, SIP Server 122 may manage a SIP Address of Record (AOR) on behalf of SIP Device 110. SIP Device 110 may register with SIP Server 122 and send SIP signaling through SIP Server 122 to other SIP elements, such as SIP Element 130 and SIP Element 132. For example, a call to the SIP AOR may be delivered to SIP Server 122, which in turn delivers the call to SIP Device 110. SIP Server 122 may perform some service on behalf of SIP Device 110, or may simply forward SIP messages to and from SIP Device 110. SIP Device 110 communicates through IP Network 124 to SIP Element 130 and/or SIP Element 132.
SIP Element 130 and SIP Element 132 may represent users with which the user of SIP Device 110 communicates. SIP Element may be a SIP Device, SIP Server, and/or other SIP enabled device. In addition, SIP Element may also represent a PSTN device that may be reached by a gateway that, directly or indirectly, acts as a SIP User Agent.
In single-line devices, an emulated call parking process may be implemented by a SIP Server 122. In this example, the SIP Server 122 may manage and maintain most of the call parking functionalities. For more sophisticated or more capable devices, e.g., a multi-line telephone devices that can manage multiple simultaneous dialogs, a SIP User Agent 112 of a SIP Device 110 may play a greater role in managing the call parking features.
As shown in
The various components of systems 200 and 300 as shown in
The call parking service in PSTN may be considered a variation of a call transfer. In call parking, however, a call may be transferred to a “parking place” (or “parking address”). While a call transfer service provides a subscriber the opportunity to converse with the transfer target before completing the transfer, a call parking service may complete the transfer immediately. Furthermore, call parking may allow the subscriber to resume the parked call from the same device or from another device. The call may also be picked up by another subscriber altogether, where the subscriber knows or is capable of receiving the codes corresponding to the parked call. As a result, a call parking service may provide tremendous flexibility.
At step 510, a SIP server 122 may be configured to identify an active call. In one embodiment of the present invention, an active call may include an SIP server connecting a first dialog D1 and a second dialog D2. In this example, a user at a SIP element 130 who calls a user at a first SIP Device (or SIP device A) 110 may transmit an INVITE message to a SIP Server 122. In one embodiment of the present invention, a SIP server 122 may include a packet switched network server. Once the SIP server receives and accepts the INVITE message, a first dialog D1 may be established between a SIP element 130 and the SIP server 122. As a result, SIP Server 122 may send an INVITE message to the first SIP Device 110 (target party). When the first SIP Device 110 receives and accepts this INVITE message from the SIP Server 122, a second dialog D2 may be created. Thus, an active call is established (and identified) by the SIP server 122 when the first dialog D1 is connected to the second dialog D2. As a result, the users and parties involved in the call may talk, converse, or share other types of information.
During the call, a user may decide to “park” the call. For example, the user at the first SIP device 110 may desire to park the call and resume the call at a second SIP device 150. In this example, the user may place the second dialog D2 on hold by performing a hook flash or other action.
At step 520, the SIP server 122 may identify the second dialog D2 when placed on hold. When a the second dialog D2 is successfully placed on hold, the user may receive and hear a dial tone to indicate that the active call has been placed on hold. Alternatively, first SIP device 110 may process the hold of the second dialog and provide dial tone to indicate the hold has taken place. Other various embodiments may also be provided.
At step 530, a user may dial a call park request code, e.g., a vertical service code (VSC), other predetermined alphanumeric combination, or other identifier, to invoke the call parking feature. In addition, the use may perform an action (e.g., voice a command, etc.) to invoke the feature. In one embodiment, first SIP device 110 may send an INVITE message to SIP server 122 along with the call park request code. The SIP server 122 may receive and accept the INVITE message and create a third dialog D3 with first SIP device 110. In addition, the SIP Server 122 may also identify the call park request code from first SIP device 110. In one embodiment of the present invention, the call park request code may include a parking address code. The parking address code may include a predetermined alphanumeric combination or other identifier that maps to a specific parking “space” for the held dialog to be parked. In this example, there may be a multitude of parking spaces available at the Call Park Server 140. Thus, when a user or subscriber enters the specific call park request code and the parking address code, a call may be parked at a parking space corresponding to the parking address code. Other various implementations may also be considered.
At this point, the SIP server 122 may transmit an INVITE message to the Call Park Server 140. Once the INVITE message is received and accepted, the fourth dialog D4 is created, as depicted in step 540. At step 550, the SIP server 122 may disconnect the first dialog D1 from the second dialog D2. At step 560, the SIP server 122 may reconnect first dialog D1 to the fourth dialog D4. This connection effectively “parks” the active call. In one embodiment, an audio session may be established between the SIP element 130 and the Call Park Server 140 such that the user at the SIP element 130 may hear music or other sounds indicating that the active call is parked. The second dialog D2 may be terminated.
A user, after parking the call in a designated parking place, may seek to resume the call from a second SIP device (SIP Device B) 150. The second SW device 150 may in fact be the same as the first SIP device 110, but in another embodiment the second SIP device 150 may be different from the first SIP device 110. At step 570, the SIP Server 122 may establish and identify a fifth dialog D5 with the second SIP device 150 once it receives and accepts an INVITE message, along with the call pickup request code and parking address code (if one was previously entered), from the second SIP device 150. In the case where a parking address code was never or improperly entered, the entry of the call park request code may be sufficient for the SIP Server 122 accept the INVITE message and create the fifth dialog D5. In one embodiment, the call pickup request code may be the same as the call park request code. In another embodiment, the call pickup request code may be different from the call park request code. Other various embodiments may also be implemented.
Once the fifth dialog D5 is created, the SIP server 122 may disconnect the first dialog D1 from the fourth dialog D4, as depicted in step 580, to “unpark” the call. At step 590, the SIP server 122 may reconnect the first dialog D1 with the fifth dialog D5 and the user at the second SIP device 150 may resume the active call with a party at the SIP element 130.
In an embodiment of the present invention, a notification may be provided by the SIP Server 122 to at least one SIP device 110 when a parked call is not retrieved for a predetermined period of time. In this example, a SIP device 110 may notify a user, for example, by a ringing signal, based on certain conditions. For example, the user may be notified if a call pickup request code is not identified at the second device within a predetermined time period. In addition, the user may be notified if the SIP server does not identify a new user dialog within a predetermined period of time. In another embodiment, a parked call may be sent back to the SIP device 110 that originally parked the call. In this example, the SIP device may provide a notification, e.g., a distinctive ringing pattern, with an expectation that a user answer the call. This ringing may continue until the parked call is retrieved. Alternatively, the notification may end after a predetermined period of time has passed. In this case, the parked call may remain parked if the device does not go off-hook. Other notifications and ringing patterns may also be considered, e.g., a “splash ring,” etc. A “splash ring” may be a single brief burst of ringing that is performed at a device, such as a telephone. In a SIP signaling, a SIP device that wishes to be notified may include subscribing to a relevant event at a server, receiving a NOTIFY message, and performing the splash ring. In yet another embodiment, a parked call may remain parked indefinitely (if it is never retrieved) with no notification of any type. Other conditions may be applied. Other various embodiments may also be considered.
In another embodiment of the present invention, a call parking service may be implemented for other devices. Such devices may include multi-line telephones that are capable of managing simultaneous multiple dialogs. In this example, a SIP User Agent 112 of a SIP Device 110 may perform a call parking service where the User Agent 112 of a SIP device 110 may be in a unique position to associate with the services of a particular dialog more easily.
At step 710, the SIP User Agent 112 of a first SIP device 110 may identify a first dialog 610 between a first SIP device 110 and a SIP element 130 when a user performs a hook flash, for example, to place the first dialog 610 on hold. In this example, the first dialog 610 may be an active call. Also, the first dialog 610 may also be between at least two SIP devices or at least one SIP device 110 and at least one SIP element 130. Other various embodiments may also be provided. When the first dialog 610 is successfully placed on hold, the user may hear a dial tone at first SIP device 110 or observe another indicator.
At step 720, the SIP User Agent 112 of the first SIP device 110 may identify a call park request code. Similar to single-line call parking, a call park request code in a multi-line device may include, for example, a VSC, other predetermined alphanumeric combination, or other indicator or code. In an embodiment of the present invention, the call park request code may also include a parking address code. The parking address code may include predetermined alphanumeric combination or other code that indicates a specific “parking space” for the first dialog 610. Alternatively, a parking address code may be automatically assigned (e.g. equal to the phone number of the parking party). In this example, the Call Park Server 140 may provide a number of “locations” or “parking spaces” for held calls. The parking address code may be mapped to a parking address at the Call Park Server. Other implementations may also be considered.
The first SIP Device 110 may transmit a REFER request to the parking address, such as Parking Place P, with parameters specifying that an INVITE message is to be sent to the SIP Element 130. In this example, the INVITE message may include a header specifying that a second dialog 620 replace the first dialog 610. Parking Place P may then send the INVITE message to the SIP Element 130 as well as a NOTIFY message for the implicit REFER subscription to the first SIP device 110. In one embodiment, the body of the NOTIFY message may contain a response code, e.g., a “100” response code.
At step 730, the SIP Element 130 may accept the INVITE message from the parking address. When the INVITE message is accepted, a second dialog 620 may be established when a response code, e.g., a “200” response, is received at Parking Place P. The SIP element 130 may also send a BYE request to the first SIP device 110 to terminate the first dialog 610, as depicted in step 740. Once the first SIP Device 110 receives from Parking Place P a NOTIFY message containing the response code, e.g., the “200” response code, the “park” operation of the active call may be effectively achieved.
At this point, the parked call may be picked up the user who parked the call or by any authorized user. An authorized user may include a user who has the call park request code information, a user capable of receiving that information, or other authorized user. To retrieve the parked call, the user of the first SIP device 110 may perform an action to request that the call with the SIP Element 130 parked at Parking Place P be picked up. The action performed may include making a second SIP device 150 to go off-hook and provides the call park request code and/or parking address code. Other various actions may also be considered. In one embodiment of the present invention, the second SIP device 150 may be different from the first SIP device 110. In another embodiment, the second SIP device 150 may be the same as the first SIP device 110.
Once the second SIP device 150 goes off-hook, the second SIP device 150 may send an INVITE message to Parking Place P, as depicted in step 750. When Parking Place P accepts the INVITE message, a third dialog 630 may be established between the second SIP device 150 and the parking address. Parking Place P may then send a REFER message to the SIP Element 130, where the parameters specify that an INVITE message be sent to the second SIP device 150. In an embodiment of the present invention, the INVITE message may include a header specifying that a fourth dialog 640 replace the third dialog 630.
At step 760, the SIP Element 130 may transmit the INVITE message to the second SIP Device 150 as well as a NOTIFY message for the implicit REFER subscription to Parking Place P. In one embodiment of the present invention, the body of the NOTIFY message may contain a response code, such as a “100” response code. Once the second SIP Device 150 accepts the INVITE message, a fourth dialog 640 may be established when the second SIP device 150 sends a response (e.g., a “200” response) to the SIP Element 130.
At step 770, when the fourth dialog 640 is created, Parking Place P may receive a BYE request from the second SIP device 150 to terminate the third dialog 630. SIP Element 130 may then send a NOTIFY message containing a “200” response code to Parking Place P. Once Parking Place P receives the NOTIFY message and sends a BYE request to the SIP Element 130, the second dialog 620 may be terminated. The fourth dialog 640, which is the only dialog not yet terminated, may effectively become the “unparked” call, from which the user and at least another party may resume dialog to complete the call park retrieval process.
The emulation of the call parking process as disclosed above may be advantageous for several reasons. An embodiment of the present invention may assign a well-known identity (implicit or explicit) to the parking place. As a result, the parked dialog or call may have a distinct parking place identity. Furthermore, an embodiment of the present invention may pick up parked calls by sending a request or message to the parking address, which in turn may transfer the parked call to the user requesting to resume the parked call. These distinct features may work together to make the various embodiments of the present invention a significantly better match to the familiar call park behavior as seen in the PSTN. In addition, an embodiment of the present invention may provide a simpler implementation for a SIP device to replicate the PSTN call park behavior. Other various embodiments for enhancing the call parking service may also be considered.
In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.
This patent application claims priority to U.S. Provisional Patent Application No. 60/719,465, filed Sep. 22, 2005, which is hereby incorporated by reference herein in its entirety.
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Number | Date | Country | |
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60719465 | Sep 2005 | US |