SS7 Link Monitors More new technology that will affect billing

Billing continues to play a key role as local number portability (LNP), advanced intelligent network (AIN) services and interconnection issues intensify. ILECs must be able to track usage on their networks, both voice and SS7, to a level of detail never seen before so they can bill CLECs for specific network usage. Interim solutions for interconnection billing, such as "bill and keep" and charging flat rates, are becoming less desirable for ILECs from an economic and strategic standpoint, and most will be eliminated soon. Usage-sensitive billing for SS7-based services and interconnection wasn't necessary in the past because carriers didn't have to provide access to their SS7 networks, and there was no mandate on local number portability. Until recently, technology didn't exist for collecting call termination data, and internetwork traffic estimates showed that "bill and keep" was basically effective.

Today, SS7 traffic is on the rise because of the growth of AIN services. LNP also affects SS7 traffic, especially because of the associated increase in database queries. ILECs have the right to charge for the signaling resources they provide. They must recover the costs that will result from SS7 network expansion and increased traffic. "Incumbents are saying 'okay, I have to let you [competitors] into my network and my databases, you can use my transmission media, and I have to terminate calls for you, but come hell or high water I want to get paid,'" says Kevin Keough, vice president of new business development at Inet Inc. of Plano, Texas.
Taking a Close Look at SS7

All the data needed for these types of usage-sensitive billing is available on the network. One way to collect this data would be to upgrade every end office and access tandem switch with new software. This would take a massive amount of time and money to reengineer and would increase each switch's processing burden. Relatively new technology, however, can enable the necessary data collection at a much lower cost, using SS7 link monitors. An SS7 link monitor takes call data off the SS7 network at the signal transfer point (STP), thus monitoring each SS7 link between switches.

The STP is a "convenient place to monitor a concentrated source of data," says Scott Bryden, product manager for SS7 billing at Hewlett Packard. This is because there are far fewer STPs than switches, and SS7 packets carry detailed data about every call that crosses the network, he says. SS7 data can be collected without interfering with the signaling network or placing any extra burden on the STP.

What is an SS7 link monitor?

An SS7 link monitor is essentially an information gathering system. As SS7 packets pass through an STP, their data is replicated and filtered by customized hardware and software attached to the STP before being transported to a centralized system based in, for example, a network operations center. (See photo on page 29.) The ideal method for managing SS7 data, says Keough, is to extract it "from the links and process it as quickly and as locally as possible so what is transported back across the network is a very high level of information. The wrong way to do it is to transfer all of the information back to a central location so that what you've done is essentially replicated the signaling system." The central platform itself could be a UNIX workstation or some other customized data processing and storage platform. A number of different applications may be attached to the core system to support anything from interconnection billing to traffic management to fraud prevention. The two main providers of this technology are Hewlett Packard (HP) and Inet. HP uses its own UNIX workstations to support its AcceSS7 link monitoring software, while Inet has designed a custom chassis, expandable with additional processing boards, as the central platform for its GeoProbe product.

How can this technology benefit an ILEC, CLEC or wireless carrier?

SS7 packets carry specific messages regarding every call made on the network. "Everything you see in an SS7 packet is essential. Within [the packets] you have originating point codes that identify the switches involved. You also have what is called an initial address message which can give you the called number and the calling number," says HP's Bryden. SS7 packets also carry information about the AIN services activated for every call. Because this data is accessible, it is possible to track call origin, destination, the route and number of switches involved, session length, any special services used and exactly how those services were provided. It is possible to track how much extra SS7 capacity or time was used for database dips and/or any extra messaging. All this data can be correlated to construct a complete view of every call, allowing an ILEC to measure exactly how much of its SS7 resources are being used by a competitor's customers, and enabling gathering of a level and type of billing detail that would otherwise be impossible. The SS7 network can therefore become not only a means of signaling and service providing, but also a genuine source of revenue.

Benefits of Usage Detail

As mentioned earlier, upgrading every switch to measure trunk usage from interconnection is both cost- and time-prohibitive. SS7 packets identify the origin of every call, so an ILEC can reconstruct exactly how many calls it terminates for its competitors. "Bill and keep" becomes unnecessary, which is extremely beneficial to incumbents who are likely to terminate a much greater volume of calls for any one competitor than vice versa.

Billing for local number portability is also at issue. While regulations regarding such billing have not yet been introduced, ILECs may have an opportunity to present precise data on how much local number portability costs them, and perhaps be able to bill for LNP on a detailed usage basis in the future. With link monitoring technology ILECs now have "a mechanism by which to track how complicated that [LNP] transaction was and prorate it or make it more expensive based on that," says Keough. "It gives the ILECs a vehicle by which to collect and aggregate data so they can show the FCC, or whoever it is, that hey, it costs this much to do it and I want to be able to bill for it."

LNP requires a number of database queries and sophisticated call routing, all of which requires extra SS7 bandwidth. ILECs want to be compensated for what amounts to a federally mandated increase in SS7 usage. Bryden points out: "Many of the LECs are building out their [SS7] networks simply to cope with LNP." Network expansion is extremely expensive and ILECs feel the need to recover and benefit from these costs. Link monitoring technology may allow them to state and defend their case, and perhaps eventually bill for LNP on a precise level.

Finally, link monitoring technology may fundamentally change the way carriers look at billing. Billing traditionally has been a switch-centric science, but not anymore. An SS7 link monitor can collect billing data more efficiently than switches because it requires fewer collection sites and is based on a central platform. A centralized platform also means that any necessary software changes or upgrades can be made at one location, rather than multiple switch sites.

A link monitor can also provide more software flexibility. For example, Inet provides its customers tools that allow them to make changes and upgrades, and even code directly onto the system, without assistance from the vendor. Managing switch software, however, generally involves multiple software packages, several different vendors, numerous software licenses and a mixture of hardware and software vintages; it is therefore an extremely complicated and expensive task. "There's a cross savings associated with using the SS7 network for replacing some of the existing billing infrastructures," says Ross Anderson, project manager for SS7 integration at Unisys. "We've had some interest in that in Latin America. They'd like to be able to get away from having to rely on switch manufacturers. They're restructuring the way they bill their customers so they can use link access technology to simplify and reduce the overall cost of their entire billing process." As has been said many times, billing is changing and so are the budgets associated with it. Billing managers must be aware of new technologies, such as link monitors, when considering how to proceed with redesigning billing processes.

Benefits for CLECs

While the ILECs are collecting billing data from the SS7 network, the CLECs will be the recipient of the bills. A CLEC thus has two choices: It can depend on an ILECs billing accuracy and just pay up, or it can do some monitoring of its own. A facilities-based CLEC can monitor the links between its network and the ILEC network so that it can verify that it is being billed correctly for trunk usage and other services. Furthermore, like the ILEC, a CLEC can measure the number of calls it terminates for the ILEC or another CLEC and bill accordingly. This would be especially beneficial to larger CLECs who, similar to the ILECs, are likely to terminate more calls than their smaller competitors. A CLEC, or any carrier for that matter, might also benefit from a link monitor due to the marketing data collection features it can offer.

Benefits for wireless carriers

Bryden cites recent legislation when explaining how a wireless carrier may benefit from a link monitor. Only recently have wireless carriers been permitted to charge wireline carriers-namely ILECs-access charges for call termination. Previously, they had to pay access fees to the ILECs, but could not charge such fees themselves. With a link monitor, a wireless network operator can get an exact picture of the traffic coming from and going to the wireline network so it can both bill effectively and verify that it is being billed correctly. Further, because monitoring the SS7 network provides a real-time view of network activity, a wireless carrier can purchase software to use the captured SS7 data for fraud prevention. Both Inet and HP have developed such software for their monitoring platforms.

The Future of STPs

As SS7 networks are built out, the call for new STPs will grow, but those STPs need to be designed with the post-deregulation marketplace in mind. Ross Anderson, project manager for SS7 integration at Unisys, says STP developers have a "groove in the expanded number of links, but as far as tapping into the spending dollars they are on the low side. If they can provide and demonstrate more functionality that they can embed on the STP side, then their value goes up and some of the network spending will be diverted in their direction."

Embedding link monitoring functions in STPs is a matter of product differentiation. Technically, from a pure data collecting perspective, it doesn't matter if the monitor is built in or added on. From a budgetary perspective, however, the more functions a piece of hardware can provide the more monetarily attractive it becomes. There is, however, one major concern: the processing burden. Anderson suggests that "there are significant capacity issues associated with clamping onto the SS7 network and being able to filter out and capture all of the information that you need to capture." Because of this concern, Anderson believes that a mixture of embedded and add-on technology will arise depending on the situation. In a high traffic area, it might be a better idea to handle monitoring on a separate platform so that the STP just handles switching and is not overloaded. In this scenario, the add-on hardware pays for itself due to the traffic volume. In a lower traffic area, embedding the software is more economical because the capacity concerns are not as serious and expenses are lowered because extra hardware is not required. Unisys is in the process of marketing its link monitoring technology to STP vendors that are interested in embedding such functionality into their hardware.

Concerns for Billing Managers

Because SS7 link monitors will be used to collect a wide variety of billing data, they will also need to interface with billing systems. Inet claims that it can supply any billing feed a customer might require while HP is sticking with more standardized formats, such as BAF (Bellcore Accounting Format) and AMA (automatic massage accounting). These systems are being purchased and implemented now; Nynex has selected HP's system while MFS is monitoring more than 1,000 links with the Inet product. Billing managers need to be aware of those aspects of this new technology that may affect them most. "If you look at an ILEC there are multiple billing departments which have a need for this type of information [SS7 data] and some are unaware of this [link monitoring] technology being procured by their ILEC organization," suggests Anderson. Billing executives must be involved in these technical decisions.

What is SS7?

The SS7 network might be considered the nervous system of the telecommunications network. Every time a call is made, specific information-such as where the call needs to be routed and what services need to be supplied-also must be transmitted. In the past, signaling was done in-band, or along the same network path as the call itself. The call was preceded by a rapid burst of audible tones that provided the proper signaling and routing information.

This method is inefficient, however, and cannot effectively support the types of IN services now in demand. Today, the SS7 network is used for signaling. It is a standardized, packet-switched data network that runs adjacent to the voice network. SS7 packets carry call origination and destination information as well as all other information needed to set up a call, such as any AIN services requested for a given call. SS7 signaling is out-of-band signaling and is far more functional and efficient than the old in-band method: More information can be delivered with SS7 packets without using up additional bandwidth on the voice network.

What is an STP?

An STP is a dedicated packet switch used only for SS7 signaling. STPs reside between the originating, access tandem, IXC and terminating switches. The STP receives SS7 packets produced by specialized software on the originating switch. This information is forwarded along the SS7 network, not necessarily parallel to the voice network, perhaps to a tandem or IXC switch, then to another STP, and eventually to the terminating switch. There may be even more switches involved, but this example gives a basic look at the system. Notice that because all of the information related to network traffic has to pass through STPs at some point, the STP is a logical and easy place to monitor and collect this information. Also realize that while this particular example is linear, an STP may in fact be surrounded by connecting switches with traffic coming from all directions. Thus, one STP can report on the activities of a much greater number of switches, and can do so in real time. Therefore collecting data at the STP is much more economical than trying to collect the same data from end office switches.