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Integrating IBM WebSphere Telecom WebServices Server with media serverA system and method for handling calls in an NGN network

Skill Level: Intermediate

Dhandapani Shanmugam ([email protected])Senior Staff Software EngineerIBM

Raghu Juluri ([email protected])Senior Member Technical StaffOracle

13 Jan 2011

This article introduces IBM WebSphere® Telecom Web Services Server, discussesintegrating its call handling features with media server, and demonstrates how IBMproducts serve the end-to-end requirements for next generation network’s (NGN)telecommunications infrastructure in handling calls on the IP based-network.

Why do we need integration between WebSphere TelecomWeb Services Server and media server?

In today's world, we often perform multiple tasks such as attending telephone calls,attending conferences, sending multimedia messages, and maintaining more thanone telephone number per person. Because of this multi-tasking, we cannot alwaysaddress incoming telephone calls immediately, which can cause disappointment forthe rejected callers and frustration for the intended recipients.

This article addresses these types of scenarios in an IP-based telecommunicationsnetwork and exhibits on how integrating the capabilities of WebSphere TelecomWeb Services Server with media server can help.

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What is WebSphere Telecom Web Services Server?

IBM WebSphere Telecom Web Services Server allows telecommunications serviceproviders (TSPs) to expose high-level web service interfaces to network services forthird parties.

Third parties are typically telecommunications service providers or organizationaldivisions wanting to develop new services that integrate with their networkinfrastructures.

Web service interfaces provide access to service capabilities in atechnology-independent way, using programming languages. Each web serviceinterface has multiple backend implementations for connecting with a serviceprovider's environment. For example, a web service interface may connect to thenetwork through the Session Initiation Protocol (SIP), the Parlay gateway using theParlay Connector, the native protocols, or by using the custom integrated services.

As depicted in Figure 1, WebSphere Telecom Web Services Server consists of thefollowing: access gateway, service policy manager (SPM), service platformcomponents, and service implementation.

Figure 1. Overview of WebSphere Telecom Web Services Server

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The access gateway provides policy-driven traffic monitoring, message capture,authorization, and management capabilities. These services are provided at theapplication layer and are enforced for each web service request using knowledge ofthe requester, target service, and invoked operation. This component consists ofmany mediation primitives where each mediation primitive provides a dedicatedfunctionality (shown as MP1 through MPn in Figure 1). For more details, refer to theWebSphere Software for Telecom Information Center (see Resources).

The service policy manager provides management, storage, and retrieval functionsfor the policy configuration data and the runtime data used to customize servicedelivery for a given requester. An enterprise-level administrator can use the SPM tomanage definitions of third-party requesters, service definitions, and servicerelationships. Using policy management capabilities, administrators can personalizethe services that are provided to groups and to individual requesters in a way that isscalable.

The service platform components provide common service implementation functionssuch as admission control, traffic shaping and usage record. These common,reusable functions are used by the service implementations and can be utilized tosupport custom built services. For more details, refer to the WebSphere Software forTelecom Information Center (see Resources).

WebSphere Telecom Web Services Server supports a large number of web serviceimplementations (SI1 through SIn in Figure 1), many of which are based on Parlay X2.1. Terminal location, terminal status, short messaging, and call handling areexamples of the services. For more details, refer to the WebSphere Software forTelecom Information Center (see Resources for the link).

What is the call handling service implementation?

The call handling service implementation (call handling SI) is a Parlay X web serviceallowing third party web services-based applications to establish routing and callhandling rules which the service executes when receiving a SIP network-initiatedcall. The call handling SI provides a mechanism for an application programmer tospecify how calls are to be handled for a specific mobile number or a group ofmobile numbers without requiring a lot of telecommunications knowledge.

These are the operations supported by the call handling SI:

• Set rules: This operation sets the call handling rules for the mobilenumber. If a set of rules is already in place for the address or mobilenumber, then this operation will replace the old rules with the set providedin the operation. Please refer to Scenario 1 depicted in Figure 2 for thedetails of this operation.

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• Set rules for group: This operation is a super set of the set rules operationwhere call handling rules can be set for a group of numbers. If rules arealready in place for any of the addresses, then this operation will replacethe old rules with the set provided in the operation.

• Get rules: Use this operation to retrieve the rule set for a single mobilenumber. The operation does not support a group of mobile numbers.Please refer to the Scenario 2 depicted in Figure 3 for the details of thisoperation.

• Clear rules: Clears the call handling rules associated with the specifiedmobile numbers. It accepts a single number as well as a group of mobilenumbers.

This is a list of the rules supported by the call handling web service:

• Call accepting: Only accept calls from a list of mobile numbers (which arespecified when setting the rule).

• Call blocking: Block calls for the mobile numbers which are in the blocklist.

• Conditional call forwarding: Route the destination of a call to anothermobile number for a specific calling number.

• Unconditional call forwarding: Route the destination of a call to anothermobile number regardless of the calling number.

• Play audio: Initiate audio with the caller by routing the call to a mediaserver or by retrieving the audio files from a repository.

Scenario 1: Set a rule

Look at the example of setting a rule in Figure 2.

Figure 2. Set rule





Here are the steps for setting a rule in this example:

1. Raghu wants to set a rule for handling incoming calls to his mobile phone.The possible rules are accept call, block call, call forward, or play customaudio messages.

2. He accesses the web application exposed by the TSP from the mobilephone via the GPRS (General Packet Radio Services) connection or froma computer through the Internet connection. The web application collectsthe data required to set the rule.

3. The web application makes a web service call to the call handling SI.

4. The call handling SI sets the rule and stores it in the database againstRaghu’s number.

Scenario 2: Retrieve the rule and act (accept call)

Look at the example of retrieving and acting upon a rule in Figure 3.

Figure 3. Retrieve rule





Figure 3 depicts the scenario of retrieving the rule and accepting the call.

1. Dhandu is attempting to call Raghu.

2. TSP network routes the call request to the call handling SI.

3. Call handling SI performs a lookup for the rules already set to handle thecall. The rule in place is “accept call”.

4. The call handling SI checks Raghu’s status and his current status isavailable. Since Dhandu’s number is in the “accept call” category, the callhandling SI will route the call to Raghu via TSP network.

5. The TSP establishes a call session between Dhandu and Raghu.

What is a media server and its role in telecommunications?

In general, a media server is a dedicated computer in the distributed computernetwork for storing and sharing various digital media such as digital videos, movies,audio, music, and picture files.

In a telecommunications domain, a media server is the processing system thathandles the audio and video streams associated with telephone calls or connections.





A media server is responsible for processing digital audio and video data. Thetelecommunications wireless systems are moving toward 4G systems where theywill be predominantly based on IP technologies namely voice over IP (VOIP) andSIP. In this environment, the concept of media servers is becoming more attractivein the telecommunications world.

Example media servers are:

• MXF media server bundles video, audio, and programmed data, such astext – together termed essence – along with metadata and places theminto a wrapper. This enables increased flexibility, performance and costsavings through the use of an IBM open standard.

• IBM Content Manager VideoCharger delivers audio and video media bypushing them over the network to the client. The audio and video contentis streamed (that is, delivered in real time) and does not require that thefile be downloaded or saved before being played by the client. For moreinformation, see Resources.

Integration of WebSphere Telecom Web Services Server withmedia server

The call handling SI has features for handling the telephone calls made to anynumber based on the status (busy, no answer, and not reachable) of the callednumber. Media server is used for providing a predefined audio and video statusmessage to WebSphere Telecom Web Services Server for handling the incomingcalls.

A practical scenario: Retrieve the rule and act (play custom audio message)

Figure 4 shows the steps when playing audio.

Figure 4. Retrieve the rule and play audio





Here are the steps for retrieving the rule and playing a custom audio message:

1. Dhandu is attempting to call Raghu.

2. The TSP network routes the call request to the call handling SI.

3. The call handling SI performs a look up for the rules already set to handlethe call. The rule in place is “play custom audio message” when Raghu'sphone status is busy.

4. The call handling SI attempts to check Raghu’s status by interacting withTSP network.

5. The TSP network retrieves Raghu’s latest status; the status is busy.

6. Since Dhandu’s number is in the “play audio upon busy” category, the callhandling SI will route the call to the media server.

7. The media server plays the customized audio as a live stream to Dhandu.

Message flow





Figure 5 shows the messages flowing among the phones, the call handling SI, andmedia server.

Figure 5. Message flow

Here are the messages in sequence:

1. Dhandu attempts to call Raghu. A SIP Invite request is routed to the callhandling SI by the TSP network infrastructure.

2. The call handling SI returns a 100 trying sip response to Dhandu.

3. The call handling SI attempts a SIP Invite to Raghu.

4. Since Raghu’s number is busy, the 486 busy SIP response is returnedto the call handling SI.

5. The call handling SI performs a lookup for the rules already set onRaghu’s number. Since Dhandu’s number is in the “play audio upon busy”





category, the call handling SI will route the call to the media server, andsend a 181 forward (call is being forwarded) session progressresponse to Dhandu.

6. The media server sends a 180 - ringing SIP response to the callhandling SI, which then routes the response to Dhandu.

7. The media server sends a 200 - OK SIP response to the call handling SIwhich routes the response to Dhandu.

8. Dhandu sends an ACK SIP response as an acknowledgement response tothe media server.

9. A session is established between Dhandu and the media server. Themedia server plays the customized audio as a live stream to Dhandu.

10. Dhandu sends a Bye SIP response to the media server to terminate thesession after the audio message has been sent.

11. The media server sends a 200 - OK SIP response to Dhandu as anacknowledgement.

Conclusion

In this article, we introduced the IBM WebSphere Telecom Web Services Server,and the role of a media server in the context of a telecommunications domain. Wehave discussed how a recipient in the IP telecommunications network can set uprules, such as, accept list, block list, call forward, play audio, and how the configuredrules can be retrieved and applied when a user attempts to call the recipient. Wealso looked at a practical scenario of how customized audio messages can bestored in the media server and played as a live stream to the caller based on therecipient’s rule setting.





Resources

Learn

• IBM WebSphere software for Telecom Information Center: Read the productdocumentation for IBM telecommunications products.

• IBM WebSphere Telecom Web Services Server product documentation: Findproduct documentation for this IBM product.

• Media server: Learn more about media servers.

• IBM Content Manager VideoCharger: Access several product manuals and allthe support information for this product.

• IBM Service Provider Delivery Environment Framework Industries: Explore thisopen, scalable, flexible telecom industry framework.

• IBM developerWorks Industries: Find the latest industry-specific technicalresources for developers.

• developerWorks podcasts: Listen to interesting interviews and discussions forsoftware developers.

• developerWorks technical events and webcasts: Stay current withdeveloperWorks technical events and webcasts.

Get products and technologies

• IBM trial software: Evaluate IBM software products in the method that suits youbest. From trial downloads to cloud-hosted products, developerWorks featuressoftware especially for developers.

Discuss

• developerWorks blogs: Get involved in the developerWorks community.

About the authors

Dhandapani ShanmugamDhandapani Shanmugam is a solution architect in the IndustrySolutions Communication Sector team in IBM India Software Labs,Bangalore. With over 10 years of IT experience, Dhandapani hasworked on many IBM middleware products for the Telecom domainincluding IP Multimedia Subsystems/WebSphere Software for Telecom,WebSphere Everyplace Server for Telecom, WebSphere EveryplaceAccess, and WebSphere Everyplace Mobile Portal. He holds patents inthe functional areas of Mobile, Telecommunications, Enterprise



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http://en.wikipedia.org/wiki/Media_server

http://www.ibm.com/software/data/videocharger/support.html

http://www.ibm.com/software/industry/telecommunications/

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http://www.ibm.com/developerworks/podcast/

http://www-128.ibm.com/developerworks/offers/techbriefings/

http://www.ibm.com/developerworks/downloads/

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Middleware Application Servers, and XML. He has co-authored an IBMRedbook on Telecom Web Services Server, and has authoreddeveloperWorks articles for Pervasive solutions. Dhandapani holds aMaster of Science degree in Software Systems from Birla Institute ofTechnology & Science, Pilani, and a Bachelor of Engineering degree inElectronics & Communication Engineering from Bhartiyar University,Coimbatore.

Raghu JuluriRaghu Juluri is a Senior developer in Oracle India Development Center,working on the Oracle Beehive collaboration platform. Prior to this, heworked as a developer for WebSphere Software for Telecom productsin the IBM India Software Labs, Bangalore. He has three years of ITexperience. He is a certified Oracle Java Business ComponentDeveloper and a SUN Java Certified Programmer, and has worked onWebSphere Business Services Fabric, and Telecom Content packs.Raghu holds a Masters degree from Birla Institute of Technology &Science, Pilani, and a Bachelor of Engineering degree in Electronics &Communication Engineering from Jawaharlal Nehru TechnologicalUniversity, Hyderabad.





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