Alternative SS7

Do a word search in any manual or technical document on the intelligent network or the SS7 signaling infrastructure upon which it is built for the words "choice," "options," "open" or "Internet." You’ll soon find that those words aren’t even in the SS7 vocabulary.

If you need reassurance that your word search is working, search for the word "reliability" in anything ever written about the Internet. You may feel at first like my Aunt Carol sitting at the dollar slot machine—a winner every time. Unfortunately, the Internet hasn’t been as lucky as Casino Carol. For whenever reliability and the Internet are linked in a story, it’s usually a horror story.

If you switch this little experiment around, you will find that reliability is the cornerstone of the SS7 network, and the Internet’s very success is rooted in an openness from which the flowers of choice and options spring.

Each technology’s strength is the other’s weakness. And until recently, the two had served disparate needs. Convergence is changing that.

The Internet’s story is in front of us every day, but SS7’s story, now perhaps taken for granted, bears repeating. SS7 helped establish the benchmark by which all things considered reliable are measured. It is the backbone of the public switched telephone network and the enabler of enhanced calling features.

As good as it is, however, it is not immune to humankind’s need to tinker. A little efficiency added here, a cheaper option added there, maybe a set of platform heels and a new coat of protocol-paint.

Companies, many of them new but with leaders weaned on SS7, continue to toy with the SS7 model hoping to find a crack in its armor and a niche in the marketplace. Here, we will look at six of them that, like today’s musicians who gave us alternative rock using the same instruments and chords that gave us rock ’n’ roll, now give us alternative SS7 by building on the same basic tenets as the original.

Forget IN. It’s the Internet

The alternatives to SS7 come in several forms and depend on whether you think of SS7 as a signaling protocol, a protocol suite, a network architecture or a service platform.

Some signaling gateway providers such as Performance Technologies and newcomer S-Link are just two of the many companies focusing on products based on the newest protocol alternative, stream control transmission protocol (SCTP).

Some alternatives address the control layer and some the services layer. Some companies such as Sevis Systems and Ariel try to streamline the process, while companies such as Targus Information Systems practically circumvent it.

As a company with its feet in both the SS7 and Internet camps, Nortel Networks is less of a niche player than the others are. It hopes to join the two camps in a peaceful migration toward what it calls the next generation high-performance Internet.

"Signaling is really just the message-based interaction necessary to initiate certain activities. It will certainly be a key enabler for almost every useful technology in the Internet. But in the Internet there are many forms of signaling hidden behind various applications just like SS7 is hidden behind telephony," says John Yoakum, senior manager in emerging business with Nortel’s signaling solutions group.

Having all but abandoned its focus on the traditional AIN, Nortel’s vision of the next generation network sees the role of SS7 as limited but necessary.

"SS7 will certainly be the key to interworking with all the circuit-switched networks but probably won’t emerge as the dominant signaling mechanism in multimedia communications," Yoakum says.

Nortel has pure SS7 products such as signal transfer points (STP) that now provide IP connectivity as well as signaling gateway products in its Succession family that do the interworking between the signaling and packet networks. Its mission is "making signaling in the Internet as robust and reliable as SS7 without trying to force SS7 itself into the Internet in any inappropriate way," Yoakum says.

To do that effectively, Nortel develops all of its products along the standards track of the Internet Engineering Task Force’s Sigtran working group. This line of attack puts Nortel in a position to lead in the development of new protocols.

The two protocols that will have the most profound effect on the converging SS7 and IP networks appear to be SCTP and session initiation protocol (SIP). SCTP is a transport protocol and SIP is more of a signaling protocol. Although Nortel attempts to support all the standards efforts to drive them toward the smallest set possible, according to Yoakum, the two are even more useful in combination.

"We can run SIP over something like SCTP to achieve SS7-like reliability in an IP network," Yoakum says.

While the big players such as Nortel work to shape the broader landscape view of the next generation network, smaller players are making the most out of their vignettes.

Rock the cache-bah

Dallas-based Sevis Systems also has a big picture view of the next gen architecture. However, its approach is to introduce one IP paradigm to the SS7 network at a time.

"Our overall message is that we are evolving the signaling network to be more conducive to convergence and actually converge the signaling network into a more unified network over IP," says Steve Samaniego, vice president of marketing for Sevis.

The company’s first step was to introduce TurboCache Smart Query, a non-intrusive database that collects local number portability (LNP) queries directly from the signaling network and stores them locally. Caching LNP queries, or "dips," can reduce the amount of traffic already overloading the network and thereby improves call set up time.

"If you pick up a cell phone and make a call you might get 10 to 15 seconds of dead time before connecting. A large part of that delay is the stress on the network. There is not enough bandwidth on the SS7 network [partly] because LNP is stressing it already," Samaniego says.

More important, caching saves carriers money. Even at fractions of a penny each, caching LNP dips can save service providers hundreds of thousand of dollars yearly. The cost savings creates a return on investment ratio that can’t be ignored.

LNP is just the first application where Sevis plans to apply caching solutions. "LNP is just one of a number of data requests on the SS7 network that are highly repetitive. So any of the traffic on the network that is repeatedly queried for is a candidate for caching at the edge," Samaniego says.

And caching is just the first Internet paradigm among many that Sevis will apply to the SS7 network. The company is planning to capitalize on its strong security background later this month by introducing another Internet paradigm into the SS7 network: a signaling firewall.

Longer term, Sevis is looking at developing solutions around gateway functionality and point code migration. One thing in favor of introducing a TurboCache-like product into the SS7 network is that it does not require a point code even though it is a network element within the network.

Whether or not there is a point code crisis is unclear, but typically, adding a new element and thus a new point code to the SS7 network can entail a great deal of re-configuration by a great many people, which always poses the threat of instability.

The missing links

Performance Technologies is on a mission to eliminate the expensive and sometimes underused links in the SS7 network. Through that mission the company offers not one SS7 alternative but two. The company’s new SEGway product is one of the first to market with a product based on SCTP, and it provides an alternative to long-haul SS7 links. SEGway is a small box with big potential. It has a 1 U chassis and runs Performance Technologies’ MicroLegend software. It can be deployed in several configurations, but the initial configuration is expected to be the Direct SS7 Link.

In the direct configuration, SEGway is installed at the central office (CO) and terminates an SS7 link at MTP Layer 2 and uses IP to communicate with a SEGway on the other end before converting the messages back into SS7. The goal is to eliminate long-haul, dedicated and inefficient 56K SS7 links with existing IP-based network links or even the Internet.

"SS7 networks are still growing at 16% year over year. That equates to $1.8 billion per year spent on standard public network/SS7 infrastructure. A huge chunk of that could be replaced and the cost conservatively less if they were to put those facilities over IP networks," says Reg Cable, vice president of signaling systems at Performance Technologies.

Cable says his company will target international carriers first. SEGway supports the E-1 technology used elsewhere around the world, and with the cost of international dedicated links they are a primary target for elimination.

"In a lot of cases we will be eliminating 1500 miles of dedicated SS7 link facilities with a couple of cost-effective boxes," Cable says.

SEGway relies on SCTP to perform at the level of reliability service providers have come to expect from Performance Technologies’ more traditional SS7 products, and in general, to perform at a level that anyone looking to inject a foreign component into the SS7 network would be expected to meet.

"The SCTP transport layer has a reliable multi-homing capability which gives you multiple address routing. If one connection was to fail, it would automatically reroute and synchronize the messages," Cable says.

Nortel’s Yoakum says the IETF was so impressed with the work being produced around SCTP that they insisted it run directly on IP. "That’s good news for everyone involved," Yoakum says.

Still, Cable and company know that carriers are not easily convinced. "The biggest concern RBOCs have is reliability. So if you are going to replace dedicated SS7 facilities with IP network architecture, you had better be able to prove you have reliable IP routing algorithms and the proper infrastructure to be as reliable as the SS7 network before they will take it on," says Bob Mason, director of marketing for the signaling services group at Performance Technologies.

Get your kicks on Route SS7

While Performance Technologies offers alternatives for dedicated long-haul SS7 links, Ariel addresses the back end of remote access by offering carriers an alternative to dedicated modem banks, which tie up expensive Class 5 switch ports when used for dial-up Internet access. The public network was not engineered to support this scenario. The average length of a voice call is three minutes, while Internet sessions run an average of 30 minutes, according to Ariel documentation.

Ariel’s BypaSS7 system also saves ISPs the expense and maintenance associated with implementing an SS7 gateway but still provides the functionality of SS7-based remote access.

The system is composed of network access servers (NASs) and an SS7 signaling gateway (SSG). The NAS supports V.90 and ISDN dial-up sessions received from the public network over inter machine trunks (IMTs).

"We are refining the software to [increase] the capacity of the gateways to handle more traffic. Our target is to have each gateway handle 10,000 ports of dial-up traffic," says Dennis Schneider, president and CEO of Ariel.

The SSG provides the interconnection with the SS7 network and supports signaling and call control. This enables the use of IMTs, which don’t use signaling.

Even with the proliferation of softswitches, Schneider still sees the ongoing need to address remote access.

"While the transport delivery side of the Class 4 switch network may all get replaced by some packet cloud, that doesn’t eliminate what SS7 does," Schneider says. "On the flip side, how many newly minted CLECs can even spell SS7 or know that is it not a Soviet ICBM?"

The SS7 route set capability enables load balancing across a carrier’s multiple points of presence (POPs). This reduces the number of busy signals and allows the carrier to reduce capital costs by spreading the traffic load to different POPs.

BypaSS7 can be deployed in three ways. The service described above is called "SS7 Enabled Trunk Service" and is managed by Ariel. "We only sell duplex machines and we administer them, monitor them and install them as an absolute rule," Schneider says. "Our customers are responsible for getting the A-links installed and providing floor space and power, but we do the rest and that provides lots of assurances to our customers."

Ariel also offers customized signaling, which looks more at the services side of remote access and allows carriers to develop differentiated services it can sell to its ISP customers. The third configuration is called Subscriber Delivery Service. It still uses the SSG and a NAS pair, but terminates the dial-up sessions at the origination CO and delivers the traffic over a data network to the ISP. This eliminates the need for off-net IMTs and lets the carrier handle terminations while the ISP manages authentication and the delivery of its services.

GTE/TSI has certified Ariel’s BypaSS7 for connection to its SS7 backbone network.

Bits ‘R’ us

Targus Information uses the SS7 network so its customers don’t have to. It is a simple concept that, perhaps more than any of the others in this article, has the potential to raise the hackles of the incumbent guardians of today’s relatively closed SS7 network. Yet at the same time, it provides a seemingly elegant solution to opening the information-rich databases within the IN to players who can’t afford or don’t understand signaling networks. They only understand information. And they want it.

Through a single query, Targus’ Intelligence Portal provides access to several databases including carrier service control points for telephone number related information. It is IP-based so it allows any computing device with TCP/IP capability access to the intelligence in the network.

Well, not any device.

"It isn’t available to anyone that wants it," says Dan Gallagher, senior vice president of operations at Targus. "To be a user of this data you must meet a series of qualifications, most notably the Individual References Services Group principals, the industry body responsible for looking at privacy issues."

For those who qualify, they can send a single IP query to the intelligence portal that contains the telephone number(s) they want information about and the data catalogue they wish to query. The intelligence portal validates the user and then goes out over the SS7 network to fetch the data. It converts it into an IP stream and sends it back to the requestor.

"We don’t care if the requesting entity is a media gateway controller or a PC. We just serve up raw data. We are a ‘deliver-the-bits company,’" Gallagher says.

The information Targus provides in its Data Catalog is anything in the TCAP realm, Gallagher says. It includes LNP data, caller name, data from the line information database and 800 translation.

Targus has links to the SS7 network through service bureaus as well as direct links to some of the RBOCs. Where it can’t get electronic access to the database for information, Targus goes out and buys it.

"The relationships we set up are all determined by economics. If it is cheaper to go to an RBOC directly we will. It also depends on how much data you are buying," Gallagher says.

Service providers are not the only companies looking for access to the information currently locked inside the IN. "We are seeing a large demand from call centers that handle a lot of inbound traffic. They want to know who is calling. They want to be able to route that person and verify they are who they say they are and they want to make sure the telephone number is billable," Gallagher says. "They want the intelligence that is out in the network inside their shops."

Maintaining decomposure

S-Link is a start-up signaling gateway provider that also touts a link replacement strategy for its signaling gateway product: the Savvi SG Signaling Gateway.

"Carrier voice services absolutely require SS7 connections. The question is not whether to provide SS7 connectivity, but how and at what cost," says Seamus Gilchrist, founder, president and CEO of S-Link.

S-Link sees the signaling gateway as the first next generation product to deliver a significant return on investment. This is done both by replacing existing dedicated SS7 links with IP-based networking and by supporting the growth of signaling networks without the need to exponentially increase the number of redundant links when the number of signaling end points increases.

S-Link’s corporate philosophy is to "provide its customers with unlimited options for a future that still can’t be defined." From that philosophy comes S-Link’s other product: the Savvi SP Signaling Proxy.

Savvi SP allows SS7 signaling end points to communicate directly with one another across an SCTP/IP transport in a transparent mode. In other words, no point codes.

"This makes the Savvi SP invisible to the SS7 network," Gilchrist says.

Prologue

The alternative solutions mentioned in this article hardly represent a comprehensive list. And as convergence finally begins to take place thanks in part to new protocols such as SIP, SCTP and TRIP, and innovative companies continue to develop solutions that make practical and marketable use of them, the list will continue to grow. As it does, some of these solutions may become obsolete while others become so commonplace and necessary that they are no longer consider alternative but essential.

One industry expert thinks they have a good chance. "I am a believer in this market," says David Fraley, Principal Analyst for SS7, AIN and Next Generation Signaling at Gartner Dataquest. "I believe these companies have validity. Once in a while there will be regulatory issues and people who will not want them connecting to their network, but if companies like Illuminet and TSI are connecting them, they have done their due diligence."

Fraley also echoed the sentiment that the best of SS7 will not go away. "There are somewhere in excess of 1 billion traditional public network telephone users in the world today. That will double in the next 15 years. You will still need some kind of SS7-like hierarchy in place to handle it."