Abstract:
A distributed voice mail system in a network includes a server in a control layer of the network and one or more media gateways in a connectivity layer of the network, wherein the server controls resources in the media gateways to provide distributed voice mail services.

Description:
BACKGROUND  
       [0001]    This application claims priority under 35 U.S.C. §119(e) to Application No. 60/195,223 filed in The United States of America on Apr. 7, 2000, the entire content of which is hereby incorporated by reference. 
     
    
     
         [0002]    The present invention is related to a telecommunication system, and more particularly to a distributed voice mail system (VMS) in a telecommunication system.  
           [0003]    Universal Mobile Telecommunication Systems (UMTS) provide a third generation (3G), broadband, packet-based network architecture. UMTS is endorsed by major standards bodies and manufacturers as the planned standard for mobile users around the world. The UMTS network transports text, digitized voice, digitized video, and multimedia at data rates up to and possibly higher than 2 Mbps. Once fully implemented, computer and phone users will be able to travel staying connected to the Internet with a consistent set of capabilities. Access is obtained through a combination of terrestrial wireless and satellite transmissions.  
           [0004]    UMTS employs a new core architecture, separating network layers horizontally into a call control layer and a connectivity layer. The call control layer contains the call control and session control servers. The connectivity layer handles the transport and manipulation of user plane data. Media Gateways (MGW) operate as nodes in the connectivity layer under the control of servers in the call control layer. The servers communicate with the MGWs using a gateway control protocol (GCP), e.g., H.248.  
           [0005]    [0005]FIG. 1 illustrates a function of MGWs  110 ,  120  between different telecommunication networks. An access network  130 , a core network  140 , and a public network  150  are depicted in FIG. 1. Each network may be owned by different operators and be of a different type, e.g., STM (legacy circuit switched), Asynchronous Transfer Mode (ATM) or Internet Protocol (IP). STM is currently more widely implemented, with ATM and IP currently being deployed. The call control server  100  controls the MGW(s)  110 ,  120  using a GCP such as H.248. One server  100  can control multiple MGWs  110 ,  120  or multiple servers  100  can be employed to control one MGW  110 ,  120 . The server  110  handles the call control routing through the network while the MGWs transform the data streams to the format required by the network.  
           [0006]    As UMTS evolves, telecommunication networks are also shifting from circuit switched to packet-switched networks. In circuit-switched networks, such as a public switched telephone network (PSTN), the communication circuit (path) for the call is set up and dedicated to the participants in that call. For the duration of the connection, all resources on that circuit are unavailable for other users. Packet-switched networks, in contrast, route relatively small units of data, called packets, through a network based on the destination address contained within each packet. Breaking communication down into packets allows the same data path to be shared among many users in the network. This type of communication between sender and receiver is known as connectionless (rather than dedicated). Voice calls in a packet-switched system are broken down into voice packets that are reassembled at the receiving end.  
           [0007]    Current telecommunication systems employ, among other system services, a voice mail system (VMS). A VMS collects, stores and forwards voice messages. For example, calls to a subscriber that is busy, or otherwise unavailable, are diverted to the subscriber&#39;s mailbox, where the caller is invited to leave a message by a recorded message. A VMS in current telecommunication system networks is a self-contained network element comprising a set of telecom resources, for example, signaling, dual tone multi-frequency (DTMF) for voice prompting, voice compression/decompression, and storage. Traditional SDH (Synchronous Digital Hierarchy) and PDH (Plesiochronous Digital Hierarchy) is commonly used between a Mobile Switching Center (MSC) and a VMS in first and second generation telecommunication systems.  
           [0008]    Accordingly, there is a need to efficiently use the UMTS network architecture to employ a VMS in a third generation telecommunication system.  
         SUMMARY  
         [0009]    The present invention addresses these and other concerns. According to one aspect, a distributed voice mail system in a network, includes a server in a control layer of the network and at least one media gateway in a connectivity layer of the network, wherein the server controls the at least one media gateway to provide voice mail services.  
           [0010]    According to another aspect, a method for providing distributed voice mail services in a network includes controlling at least one media gateway in a connectivity layer of the network using a server in a control layer of the network, wherein the server controls the media gateway to provide voice mail services.  
           [0011]    According to yet another aspect, a method for providing distributed voice mail services in a network includes controlling at least one media gateway in a connectivity layer of the network using a server in a control layer of the network, wherein the server controls the media gateway to provide voice mail services. A voice mail retrieval call is traversed from the media gateway to the server. Upon receipt of the voice mail retrieval call at the server, one or more corresponding coded voice mail system terminating call messages are retrieved from a storage unit by the server and traversed from the server to the media gateway. The one or more corresponding coded voice mail system terminating call messages are decoded in a codec of the media gateway.  
           [0012]    According to still another aspect, a computer program product for providing distributed voice mail services in a network is provided. The computer program product includes a computer-readable storage medium having computer-readable program code means embodied in the medium. The computer-readable program code means includes logic that controls at least one media gateway in a connectivity layer of the network using a server in a control layer of the network, wherein the server controls the media gateway to provide voice mail services. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The above and other objects, features, and advantages of the present invention will become more apparent in light of the following detailed description in conjunction with the drawings, in which like reference numerals identify similar or identical elements, and in which:  
         [0014]    [0014]FIG. 1 is a diagram illustrating the function of a MGW; and  
         [0015]    [0015]FIG. 2 is a diagram illustrating a distributed VMS in accordance with an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]    Preferred embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, well-known functions and/or constructions are not described in detail to avoid obscuring the invention in unnecessary detail.  
         [0017]    The UMTS network architecture is efficiently used in conjunction with the MGW architecture to realize a distributed VMS. The VMS supports mobile network voice mail services, for example, Call Forwarding on Busy to Voice Mail, Call forwarding Unconditional to Voice Mail, Call Deflection, etc. The invention describes the lower layer (user plane) configuration and functionality.  
         [0018]    Turning again to the drawings, FIG. 2 illustrates a distributed VMS  200  in accordance with an embodiment of the invention. The VMS  200  includes a server  250  and shared resources within one or more MGWs  210 , acting in a client-server relationship. The shared resources include, but are not limited to, a Media Stream Board (MSB)  220 , Processor Board (PB)  230 , Backplane  215 , and Interface Boards (IB)  240 ,  245 .  
         [0019]    Each MGW  210  is a self-contained network node that includes a full set of speech and data resources, collectively referred to as Media Stream Applications (MSAs). The MGW  210  conventionally functions to convey media streams from one network to another located in a path from one subscriber to another during a normal call. The invention incorporates the resources of the MGW within a distributed VMS.  
         [0020]    The MSAs are individually controlled and separated from the external transmission and addresses (connection endpoints). It is possible today to implement a MSB  220 , which can handle several different MSAs on the same physical board. The board could, for example, be implemented with a number of DSPs. Examples of MSAs include a Transcoder (codec), an Echo Canceller (EC), a Tone/DTMF sender/receiver for voice prompting at voice mail retrieval, a Conference Call Device (CCD), an Announcement Machine, and a Data Transmission Interworker (DTI). The Transcoder converts data between different voice coding formats, e.g., between PCM coded and ARM coded voice. The EC suppresses/removes echoes generated in the PSTN. The Tone/DTMF sender/receiver generates and receives tones, e.g., a busy tone or a call in progress tone. The Announcement Machine generates standard messages for announcement to the subscriber, e.g., an error message indicating a dialed number is not in use. The DTI and CCD are not accessed during a VMS session, but are nonetheless relevant to other functions performed by the MGW. The CCD enables multi-party calls. The DTI functions as a modem pool for circuit switched data.  
         [0021]    The MGW  210  provides a switching function to connect different MSAs and external connection endpoints, e.g., an IP network  280 , an ATM network  270  and/or a PSTN/lnternet  260 . MGWs are currently being developed for GSM/UMTS networks.  
         [0022]    More than one MSA is often needed for a call. For example, a Transcoder (codec) and an EC are both needed for many calls, e.g., for a mobile to PSTN/ISDN call. Thus, MSAs are typically linked in a chain, or so-called call chain. A link can either be an MSA or an IB  240 ,  245 .  
         [0023]    An IB  240 ,  245  is a board used to interface with the external network. The IB  240 ,  245  terminates the physical layer used in the network and interfaces a space switch used in the node. The space switch performs the physical sending of cells belonging to different connections to different outgoing ETs.  
         [0024]    The partitioning of functionality between the ETs and the space switch differs in different implementations. In the simplest case, e.g., for an ATM connection through the node, the ATM cell header indicates which IB  245  a cell should be sent to. The cell is then switched in the space switch to the outgoing IB  245 , which is connected to the network. The cell is switched based on the Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI), which the IB uses to refer to a connection table that indicates to which outgoing IB the cell should be sent.  
         [0025]    Switching includes both space switching and logical switching. Logical switching is performed when the VPINCI value is changed, e.g., by adding information to the cell. This information is used by the space switch to route to the cell to the correct IB  245 . The VPINCI values may be changed in either or both an incoming or an outgoing IB  245 ,  240 .  
         [0026]    When the MGW  210  is used to perform an MSA, an MGW  210  internal connection, such as backplane  215 , is used to connect the IB  245  to the MSB  220 . MSAs are executed in processors, a number of processors typically being included on a board. A plurality of boards are included in a magazine. A number of magazines are included in a node. In most existing implementations of MSAs, there are dedicated boards for each MSA, or at least for many MSAs.  
         [0027]    The MGW  210  resources are dynamically allocated to the distributed VMS  200 , similar to other applications supported by the MGW  210 . The resources allocated can be distributed among multiple boards. The resource allocation is controlled by a Media Stream Resource Manager (MSRM), which manages all of the processors on a respective MSB  220  as a resource pool. The MSRM allocates a specific MSB  220  for the processing of arriving packets and the subsequent execution of a MSA in the call chain for the packet, depending on the load characteristics for that MSB  220 .  
         [0028]    The server  250  is preferably a commercial server with a high capacity storage  255 . Alternatively, one or more PBs  230  in the MGW  210  can be configured as a server.  
         [0029]    In operation, the VMS  200  functions to terminate calls that have been diverted to the subscriber&#39;s mailbox, where the caller is invited to leave a message by a recorded message. Calls originating in a PSTN  260  are received at the IB  245  and coded in the MSB  220  codec. A connection  295  is established between the MGW  210  (via IB  240 ) and the server  250  via a packet/cell network  290 . The coded message is traversed from the MGW  210  to the server  250  via the connection  295 . The messages may be coded and traversed with generous limits for both delay and delay variation, for example every 20 ms, according to the limitations of the server&#39;s buffer size. The coded message is stored in the storage  255  of the server  250 .  
         [0030]    Ideally, the codec uses an algorithm compatible with the mobile station of the called subscriber. However, the standards for GMS/UMTS are currently silent regarding VMS terminating calls. A best effort technique can be employed by using an algorithm currently dominating the subscriber&#39;s PLMN, i.e., adaptive multi-rate (AMR). However, using the dominating algorithm will result in deteriorated speech quality for mobile stations not supporting the algorithm. Alternatively, the MSB  220  codec and mobile stations can support a current state of the art algorithm.  
         [0031]    When a call is originated in a PLMN  260 , the message is already in a coded format and can be through-connected in the MSB  220  without change. The coded message is traversed from the MGW  210  to the server  250  via the connection  295 . The coded message is stored in the storage  255  of the server  250  in the received format, maintaining the best possible speech quality.  
         [0032]    When a subscriber calls to retrieve the voice mail messages, the connection  295  is established between the MGW  210  (IB  240 ) and the server  250  via the packet/cell network  290 . The coded message stored in the server is traversed from the server  250  to the MGW  210  via the connection  295 . The coded messages are sent in bursts to minimize both delay and delay variation according to the limitations of the MGW&#39;s buffer size. The MSB  220  decodes the received coded message to another format as needed. The decoded message is then traversed from the MGW to the PSTN/PLMN  260 . During voice mail retrieval, the required DTMF functionality is provided by the MSB.  
         [0033]    The invention provides several advantages. The distributed VMS  200  is a logical node comprising the server  250  and resources from one or more MGWs  210 , in one or more networks. The resources in the MGW(s)  210 , in the one or more networks, can be dynamically allocated to the distributed VMS  200 , i.e., no resources are permanently allocated to the distributed VMS  200 . Accordingly, all the available MGW resources can be pooled, thus increasing the statistical usage of the resources and making a more efficient use of the overall network resources.  
         [0034]    A commercial server may be used, which may also be a shared resource in the network between other telecommunication applications, multiple networks, and different types of networks. The server does not need to perform many of the VMS related functions, since they are performed by the MGW  210 . For example, the server  250  does not have to perform speech coding/decoding functions or DTMF functions, since they are performed by the MSB  220  in the MGW  210 . Compressed voice is traversed between the MGW  210  and the server  250 , which reduces the amount of bandwidth required compared with a conventional pulse code modulation (PCM) technique employed by an MSC and stand alone VMS solution. This also reduces the Quality of Service (QoS) requirements on the connection between the MGW(s)  210  and server  250 . The connection need not support real time transfer, since the buffers compensate for any delay. Accordingly, existing ATM or IP networks may be used to transfer the data. The Internet may be used as a very cost efficient transport option, assuming security issues are addressed. Also, signaling can be carried on an IP network. The server may also store the announcement machine messages using the same techniques.  
         [0035]    The MSC Server  300  handles call control with wireless subscribers during a call control phase. For example, when a call is redirected to the VMS because a called mobile subscriber is busy, the MSC initiates an alert to the mobile subscriber, via associated Mobile Services Switching Centers and Base Stations, indicating there is a stored message to retrieve.  
         [0036]    While only voice calls are described above, it will be understood that the same principles can be applied to services using other data formats, such as fax and video messaging services.  
         [0037]    It will be appreciated that the steps of the methods illustrated above may be readily implemented either by software that is executed by a suitable processor or by hardware, such as an application-specific integrated circuit (ASIC).  
         [0038]    Although described with reference to a communication system, it will be appreciated by those of ordinary skill in the art that this invention can be embodied in other specific forms without departing from its essential character. For example, the invention may be used in any multi-processor system. The embodiments described above should therefore be considered in all respects to be illustrative and not restrictive.  
         [0039]    The various aspects of the invention have been described in connection with a number of exemplary embodiments. To facilitate an understanding of the invention, many aspects of the invention were described in terms of sequences of actions that may be performed by elements of a computer system. For example, it will be recognized that in each of the embodiments, the various actions could be performed by specialized circuits (e.g., discrete logic gates interconnected to perform a specialized function), by program instructions being executed by one or more processors, or by a combination of both.  
         [0040]    Moreover, the invention can additionally be considered to be embodied entirely within any form of computer readable storage medium having stored therein an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein. Thus, the various aspects of the invention may be embodied in many different forms, and all such forms are contemplated to be within the scope of the invention. For each of the various aspects of the invention, any such form of embodiment may be referred to herein as “logic configured to” perform a described action, or alternatively as “logic that” performs a described action.  
         [0041]    It should be emphasized that the terms “comprises” and “comprising”, when used in this specification as well as the claims, are taken to specify the presence of stated features, steps or components; but the use of these terms does not preclude the presence or addition of one or more other features, steps, components or groups thereof.  
         [0042]    Various embodiments of Applicants&#39; invention have been described, but it will be appreciated by those of ordinary skill in this art that these embodiments are merely illustrative and that many other embodiments are possible. The intended scope of the invention is set forth by the following claims, rather than the preceding description, and all variations that fall within the scope of the claims are intended to be embraced therein.