Developing SCPs and Intelligent Peripherals for the Wireless Market

Today's wireless customers demand personalization; anytime, anywhere access; and multi-media person-to-person messaging. Service providers are addressing these demands by adding new SS7 Intelligent Peripherals to provide key functions in enhanced services, such as customized voice announcements and voice recognition. Also critical to the implementation of enhanced mobile services is the Service Control Point (SCP), which, as its name implies, houses the service logic and provides service control and the essential link between the core SS7 network and the advanced Intelligent Peripherals.

This Application Note addresses the engineering and business planning aspects of implementing Intelligent Peripherals and the SCP. Specifically, this document explains:

• Technical needs of the current wireless market, which features services such as mobile entertainment and mobile video
• Technology trends that enable entrepreneurs to take advantage of new developments in designing new mobile services
• The issues faced by engineers when developing and deploying enhanced services

Using SS7 technology to deliver enhanced wireless services opens an exciting array of options for entrepreneurs. These systems are not simple to deploy, however, due to the carrier requirements and the sophistication of the protocols involved. Methods for coping with various issues, such as the complexity of SCP interfaces and the difficulty of implementing and testing solutions, that are described in this document are drawn from actual experience on multiple projects by PALM Associates using NMS' SS7 product suite. The emphasis on practical, first-person experience will be helpful for engineering teams embarking on the development, deployment, and testing of Intelligent Peripherals and SCPs for the wireless market.

Technology Needs of the Current Market
For the past few years, the number of wireline subscribers and minutes of use has been on the decline, while the reverse has been true for mobile subscribers. This trend is causing both service providers and the companies in the enhanced services value chain to place an emphasis on mobile markets.

Mobile Entertainment
In mobile communications, messaging generates the majority of wireless data revenue. Future revenue growth is expected to come from the mobile entertainment sector. Pictures, video, music, games, and the resulting interactions with content providers (vs. person-to-person communications) will be significant factors in this market. To illustrate the projected size of this market, the Yankee Group estimates that global mobile data services revenue will grow from $20 billion in 2002 to $100 billion in 2007 (Yankee Group 2003, NMS).

The hot mobile entertainment service that is now spreading around the globe from its birth in Korea is the user-customizable ringback tone. At its most versatile, the service allows subscribers to provision the network to play different audio (usually music) as a ringback based on the identity of the caller or the time of day, for example. The service provider charges a fee each time the subscriber defines the use of an audio clip.

The market needs for a successful mobile entertainment service, such as ringback tones, vary depending upon whom you ask. Ask a business manager involved in the mobile entertainment market what factors are important for success and the response will include a discussion about ARPU, providing the right mix of content, content management, intuitive user interfaces, and self provisioning. Ask the installation manager for the mobile entertainment system what is important and that response may include real-time call processing and centralized content and subscriber management, but definitely will include the need to connect the content system with the service provider network through SS7 call control.

From these responses, the importance of SS7 in a mobile entertainment service becomes clear. Self provisioning, content management, and other key features of a successful enhanced service are not possible without Intelligent Peripherals, the SCP, and the SS7 network. For example, for a ringback tone service, in addition to managing call establishment, SS7 enables the user provisioning and controls the playing of the audio clip during the ringback period.

Mobile Video
Another hot mobile market is mobile video — not just from an entertainment perspective, but also for communications such as video chat and video mail. The application most likely to make the mobile video market take off is two-way conversational video. But with conversational video comes the requirement for acceptable quality of service (QoS) on the mobile network. This is a challenge because video applications transmit and receive multiplexed, compressed audio and video streams over the same bandwidth previously used to send just audio. To address QoS issues, service providers are turning to 3G-324M as the protocol of choice.

3G-324M provides a low-latency, circuit-switched mechanism to deliver video data over the mobile switching office's (MSO) wireless interface to the 3G-enabled mobile video handset. The control signals from the service provider's switch to the 3G-324M gateway can be either ISDN or SS7, making mobile video a target for Intelligent Peripheral providers.

Find Me, Follow Me Service
Another service enjoying increasing popularity is the Find Me, Follow Me service. This service ensures that an individual can be located on a telephone of choice using any given phone number — home, office, or mobile. When a voicemail service or personal assistant service is added in, the result is a very useful package. The enabling technology that makes all of this work is the powerful SS7 signaling system in the service provider's network. SS7 provides the means for all the nodes within the service provider's network to communicate and coordinate and make the necessary voice circuit connections to provide users with this seamless service.

There are a number of inhibiting issues to be overcome in the provisioning of such a service, however. Having different wireline and wireless service providers is one issue. Having a work extension on a private PBX is another, as is having a Centrex work telephone number that is under the control of employers. While an aggressive, innovative service provider can most likely work through these issues and offer a Find Me, Follow Me service, the critical technology behind the service's provisioning is SS7.

Technology Trends Pulling the Market Forward

Enabling technologies are now in place for the delivery of exciting, revenue-generating, value-added services. Two examples of "hot" technologies are CAMEL (Customized Application Mobile Enhanced Logic), defined by ITU and the standard for GSM networks, and WIN (Wireless Intelligent Network), a concept being developed by the Telecommunications Industry Association (TIA) and the standard for ANSI-41-based networks.

CAMEL and WIN allow the close cooperation between an SS7 switch and an Intelligent Peripheral by using triggers to notify an application of events occurring in the call flow. They also support additional messages to deliver content and messages to subscribers. In practical terms, CAMEL and WIN allow roaming customers to take their personal "environment" with them by supporting the myriad message exchanges that are necessary to export the subscriber's environment. The key that opens up the carrier's call flow to the Intelligent Peripheral is the trigger. A trigger is an interruption to the traditional call processing. When the switch detects that a trigger is enabled, it suspends the processing of the call and sends a message to the SCP/Intelligent Peripheral to request instructions on how to proceed. In this way, the execution of the call can take a number of different paths, offering a high degree of customization that tailors the call to individual subscribers, their carrier, and the content provider.

Both the CAMEL and WIN standards specifically address the capabilities for delivering enhanced services to subscribers. For example, WIN Phase I enables calling name presentation, incoming call screening, and voice controlled type services, and WIN Phase II enables prepaid charging, VoIP, and premium rate type services. The critical ingredient necessary for delivering these services is the Service Control Point.

Importance of the SCP
The SCP communicates directly with the switch and intercepts triggers and other service-related messages from the switch or Service Switching Point (SSP). These messages are often routed to the SCP through a Signal Transfer Point (STP), which provides routing of the SS7 messages within the network. The SCP acts as the gateway between the SS7 world and the world of the Intelligent Peripheral (IP). The Intelligent Peripheral contains the content and helps the SCP decide how to deliver the enhanced services to the subscriber.

 
Figure 1: Intelligent Network Architecture

The interconnection between the SCP and the Intelligent Peripheral is sometimes Internet-based. Thus, the SCP lives in both worlds — the service provider's SS7 space and the Internet space. It heralds the approach of next-generation networks (NGN), which blend the public switched telephone network (PSTN) and the public switched data network (PSDN).

Engineering Considerations

Interfacing to a service provider's SS7 network is not a trivial task, but a number of off-the-shelf solutions are available to make this job easier. There is a bewildering complexity of protocols, switches, wireless and wireline protocols, and technologies that must be navigated before arriving at a solution. Following are descriptions of some of the primary considerations.

Protocol availability. Switch vendors typically roll out protocols in response to market demands, and service providers upgrade their switches to meet customer requirements. In some cases this means that the protocol enhancements a developer needs are not always available. There are alternatives; for example, ORREQ (an older message) can be used in place of ANALYZINFO (the new WIN message).

Capacity planning. The trend throughout the wireless market is towards higher bandwidth. For example, 3G and UMTS push the envelope of bandwidth. Network providers envision that streaming video to the handset will follow in the footsteps of Multi-media Messaging System (MMS). Engineering these considerations into a solution at the onset will eliminate costly redesign and restructuring at a later date when 3G and streaming video become widely available.

Robustness. High availability solutions are important for enhanced services because loss of service is a loss of revenue. Traditional SS7 networks are heavily redundant in order to offer the five-nines availability required by service providers. When developing an SCP and its associated Intelligent Peripheral, the design should be implemented with comparable availability considerations in mind.

Traditional SS7 telephony engineering provides abundant solutions for addressing the high availability requirement. SS7 network elements are normally configured with a "hot backup" that is switched over when one link fails. Such a switchover is possible because both instances maintain a common state about the links. The design issues for such a configuration usually revolve around how to dynamically synchronize the current state and when/how the management component decides to effect the switchover. Dual SS7 links from NMS, for example, have an automatic state updating feature that maintains the circuit and link state between two different SS7 boards using an embedded Ethernet connection. This feature will permit a management application to implement automatic "switchover" in the event that one of the dual SS7 links fails. The same process can be used to maintain a higher-level state at the ISUP (ISDN User Part) or TCAP (Transaction Capabilities Application Part) (call or data layer) interfaces.

In the Internet world, the solutions are less off-the-shelf and need to be implemented during system design and development. The analysis should include consideration of the same issues facing the SS7 side, specifically, a duplex configuration with alternate communication paths to key resources, a mechanism to maintain common state between dispersed components, a management component with the logic to measure and monitor the interface and to decide when to promote the secondary to primary status (switchover), and an efficient, rapid mechanism for effecting the switchover.

Scalability. Aggressive growth in the amount of traffic can be expected when an enhanced service is attractive to the general public. Engineering a system for this growth at the onset will pay off as the traffic and revenue grow. Messaging-oriented infrastructures, distributed system deployments, fault-tolerant hardware, and strict layering in the software all contribute to improving a system's scalability and robustness. Well-instrumented software will provide the important metrics to operational staff so they can anticipate the required upgrades. This approach leads to a proactive management philosophy in which the system and software are upgraded before a traffic crunch affects the customers.

Testing and interoperability. Evaluating a product that is intended to operate in a mixed environment such as SS7-SCP/Internet-IP requires a running environment that includes both networking technologies. While the Internet world is relatively easy to simulate, a true SS7 environment requires fairly expensive components such as a #5ESS switch or simulator. True operational testing should be scheduled in the network equipment vendor's laboratory after integration test and evaluation have been completed in a simulated environment. Central office SS7 simulators are available from suppliers or can be constructed by using boards from companies such as NMS; telephone simulators can be purchased from companies such as PALM Associates Inc., as well as other sources. This approach leaves only the full-scale interoperability issues to be resolved in the switch vendor's laboratory. and, to ensure worldwide interoperability, be prepared to test against switches from all switch vendors.

In-network operation. In addition to testing in the switch vendor's laboratories, most carriers will want to evaluate the system in the operational environment of their network. As part of switch vendor testing, a Method of Procedure (MOP) would likely have been developed that explains how to deploy and acceptance test the product. The MOP will contain descriptions of the equipment, connectivity requirements, dialing plans, switch configuration options that need to be enabled, Global Title Translation (GTT) impacts, and the messages to be exchanged, fields to be included, and responses expected from both sides, as well as recovery and fail-over procedures. In addition, the business development/marketing organizations of the operator will want to build a business case to justify any costs incurred on their side in deployment and to understand the revenue potential associated with turning on the product in their infrastructure. PALM Associates, Inc. can provide templates for both the MOP and the business case.

Approvals and certification. When deploying products, especially internationally, a key challenge is the myriad of country regulations that must be satisfied before products can be deployed. There are many steps to gaining approval of a product. First, products should be developed according to the governing telco, safety, and EMI standards. It is important to ensure that regulatory issues are considered early in the design process. Products should be pre-tested early in the development cycle to verify that these standards are being met.

Once the product hardware is released to manufacturing and the software is at beta-quality, the product can be submitted to recognized test labs for formal testing for compliance to telco, safety, and EMI standards. Test reports substantiating compliance with the relevant standards will be received once the product has passed all testing.

The next step is to submit an application form with the test reports to the appropriate governing body. Practically speaking, most countries in the world (except, for example, Korea and Australia) will accept test reports completed against either European or USA standards.

If a certified product is being used as part of a system, it may be necessary to then get that system tested as a whole. It is also possible that testing of additional equipment may be required.

It is important to be aware that the process of international approvals can be lengthy in some countries and developers should plan their development schedules accordingly. Developers can leverage NMS' international experience to bring applications to market more quickly. NMS has achieved approvals in many countries and has a worldwide network of support personnel ready to help.

Answers from PALM and NMS

Customers are asking for more capacity using the same infrastructure at a lower cost. Software-based network elements are one of the answers to these demands. For example, adding a software-based compression algorithm to an existing network infrastructure component is a simple change that permits more circuits to be served over the existing plant. PALM Associates, Inc. routinely develops software-based network elements using NMS and Intel hardware to satisfy this requirement. Using commercial-grade platforms to replace specialized hardware is another way to add more capacity at less cost. PALM Associates, Inc. has implemented a number of products to make deployment of SS7 solutions easier, saving OEMs time and money.

The PALM Advantages
Examples of PALM-developed solutions include an SS7-IP signaling gateway that manages ISUP connections for servers, such as a fax server or IVR, an SS7 monitor for tapping into SS7 and Abis communications at various points in the network, and a general-purpose SS7 platform for use in building a variety of SS7 solutions.

One such product is a high-level SS7 message processor that will take care of ANSI IS-41/D analysis, such as the ORREQ message or ANALYZDINFO. In addition, PALM's solutions handle the CAMEL INAP CS-1/CS-2/CS-3 processing. The integrated NMS boards support the SS7 protocol stack. This platform can become the essential element for a complete IP Multimedia Subsystem (IMS) product deployment, as well as handle many of the converged and 3G/4G network requirements The SS7 deployment platform can be turned into an SMS filter by adding the appropriate message processing functions.

Deploying enhanced services using a turnkey solution from PALM built on NMS enabling technology is a win-win proposition for all parties:

For the entrepreneur — Budget is fixed; no requirement to learn the complexities of SS7; development can concentrate on the value-add of the product

For the service provider — The SCP is from a known source, familiar with both SS7 and Internet technologies, thereby reducing the risk of networking problems during operation.

For the investor — Relying on NMS enabling technology and PALM expertise improves the chance of a successful product development. Known solutions reduce the risk of technical problems becoming a roadblock. PALM's extensive background of working with new start-ups means that experienced help is available in additional technical areas.

For the consumer — PALM solutions based on NMS enabling technology mean that time-to-market is shortened and enhanced services can be made available while the market is still hot.

Increased probability of success, technology risk reduction, shortened time-to-market, and product flexibility are the benefits of a PALM product based on NMS enabling technology.

The NMS Advantages
Working with NMS allows developers and OEMs to leverage NMS' expertise as a supplier of not only enabling technology, such as the TX 4000 Series of SS7 boards and its full-stack SS7 software, but also complete systems, such as the Mobile Place mobile services system, featuring the MyCaller ringback tone service. NMS estimates that it now delivers ringback tone services to 170 million consumers globally and will touch 90% of all ringback subscribers as service rollouts progress over the next 18 months.

NMS was also an early leader in providing enabling technology for the 3G-324M video infrastructures to network equipment and service providers including Fujitsu, NEC, and NTT DoCoMo. NMS has recently released video enabling technologies, Video Access, as a new service of its Natural Access development environment, enabling all NMS customers to offer video services in their applications. NMS has addressed support for video streaming in the product roadmap, and PALM Associates, Inc. is developing software support for this feature.

NMS' SS7 offerings conform to all the important worldwide standards and have been demonstrated to operate with all the major switches, ensuring ease of installation in many countries.

Global Deployments
NMS has SS7 deployments around the world and a presence on six continents:

Telecom Operator Deployments
NMS SS7 products have been installed by these operators:

Proven Interoperability
NMS SS7 products have proven interoperability with the following switches:

Government Approvals
NMS SS7 offerings have government approvals for protocols where obtainable, for example:

• Chinese Ministry of Information Industry
• Italian Ministry of Telecommunications
• Certification Labs
• NMS SS7 products have been tested in the following labs:
• AT&T TCAP certification
• KTL Labs BT-NUP certification
• Telcordia

About Palm Associates
PALM Associates, Inc. develops software products in the communications, networking, voice and security areas for new start-ups and Fortune 100 customers. PALM's expertise includes SS7, VoIP, and traditional telephony as well as solutions for carriers in the wireless and wireline communications area. PALM has implemented SCP (Signaling Control Points), gsmSCF (Service Control Function), MMS (Multimedia Messaging Systems), and VoIP (voice over IP) products, as well as portals and network elements. In addition to over a decade of software product development for OEMs and new start-ups in the communications and networking area, PALM brings a wealth of practical experience in integration and operation with the world's switch vendors. For example, using the same software infrastructure but different message processing components, PALM has integrated its NMS-based SS7 solutions with the Lucent #5ESS, Nortel DMA MTX-MSC for CDMA networks using the WIN/IS41 TCAP interface and, for GSM networks, CAMEL Phase II & III with Nortel's DMS250 MSC and HLR. Previously PALM has integrated with Ericsson switches using ISUP and with both Ericsson and Nortel switches in the Abis interface area. See www.palmcorp.com for more information.

PALM Associates, Inc.
1710 Zanker Road
San Jose, CA 95112
Tel: +1 408 441 8500
Fax: +1 408 441 0858
email: palm@palmcorp.com