VoIP Causes An Enterprise 911 Emergency

If you need to call 911 from the office, try to make sure your office is in Florida, not Colorado. That's because Florida is one of five states that require enterprise PBXs to provide emergency services with the exact location of callers, whereas Colorado is one of three with laws on the books saying they don't need to provide any location data at all. In most other states, emergency services may be able to determine only the postal address of the building containing the PBX, not the actual phone from which a 911 call was made.

That will change in 2006, when the FCC is likely to introduce regulations mandating that PBXs provide detailed location information compatible with Enhanced 911 (E-911), the technology that automatically tells 911 dispatchers where callers are. In December last year, it issued a notice of proposed rule making that gave states one year to introduce their own legislation. Some have (see "State Enterprise E-911 Laws" below, left), but the majority haven't, so the FCC is set to act and introduce national rules.

That's good news for people who need to call the cops from a sprawling corporate campus, but a potential headache for the IT managers who need to implement the capability. Some may see it as an opportunity to replace aging TDM telephony with a shiny new converged network, but VoIP has its own E-911 challenges. While most PBXs can be programmed to provide some location data, VoIP providers don't always know what to do with it. And forget about mobility outside the enterprise network: Although vendors like to demonstrate technology that can track users to within a few feet, real VoIP services are lucky if they can guess the right time zone.

ROUTING AROUND THE RULES

Superficially, VoIP's failure to provide emergency services echoes that of cell phones a decade earlier. The 911 system is largely separate from the PSTN, but both are based on the same circuit-switched architecture and were designed to work together. Dedicated 911 trunk lines link telephone exchanges to the country's thousands of local Public Safety Answering Points (PSAPs), call centers staffed by emergency dispatchers.

Each PSAP serves a relatively small area, so it's relatively simple for them to implement E-911 for PSTN lines. Nearly every PSAP now contains a database of Automatic Location Information (ALI), which maps all the phone numbers within its coverage area to a specific place--at the least a street address, and sometimes a precise location within a building. The ALI data usually pops up in front of the dispatcher's screen as soon as a 911 call is connected so that people in emergencies don't need to give directions.The FCC's attempts to push cell phone operators into providing accurate E-911 data have taken longer than safety advocates had wanted, but they've been successful for the most part. After four years of delays and extensions, regulations that require carriers to provide the PSAP with an accurate grid reference for 95 percent of 911 callers are finally coming into effect at the end of this month. To meet them, the carriers have invested heavily in location-tracking technology. Many reuse the same technology for commercial location services: The most successful is Sprint Nextel, which can track large fleets of delivery and service trucks using GPS phones.

The same isn't happening with VoIP. Although the FCC spent much of this year setting strict regulations about the availability of E-911 through VoIP, the VoIP service providers have discovered a simple loophole. Instead of actually providing E-911, they can get their customers to sign a waiver accepting that 911 services may not be available. That may be enough for home users who see Internet telephony as a way to avoid long distance calls, but not for enterprises that want VoIP to reproduce all the PSTN's functionality.

The rules affecting VoIP service providers that do try to offer E-911 can lead to absurd situations. Most VoIP providers can only offer E-911 services within the coverage area of some PSAPs, and the FCC requires them to cut off all non-emergency connectivity to customers who move outside that area. "They want us to suspend all capability except the one that we can't deliver," says Caitlin Clark-Zigmond, director of product management at New Global Telecom, a wholesale VoIP provider.Even worse, current FCC rules require that users update the ALI database manually--either by talking to a person in a call center or entering an address into a Web form (see "E-911 In a VoIP Network"). They're supposed to go through this process every time they move between buildings to avoid wasting time when calling 911.

The threat of being cut off when outside the E-911 service area gives people a powerful incentive to lie. "It depends what's important to you," says Clark-Zigmond. "We think it would be better to have the correct location of the caller, even if it isn't automatically delivered to the correct PSAP."

BLIND ALI

The underlying problem is that unlike cell phones, VoIP separates the telephony service from the physical infrastructure. That's great for people who want to take their phone service with them when they travel, but it means service providers have no way to locate customers.

"You'd need some kind of GPS or wireless system in handsets," says Fred Epler, chief scientist at VoIP provider AccessLine Communications. "And right now, no one's thinking about that. Everyone is just focused on meeting the regulations."

According to Epler, the FCC's rules have improved VoIP's 911 service somewhat, even if an accurate location isn't available yet. A year ago, many 911 calls made from VoIP phones didn't get through at all. There were few official ties between PSAPs and VoIP providers, so calls were often routed over the Internet and PSTN rather than the dedicated 911 network. Many ended up at the PSAPs' administrative lines, which aren't always answered.

The situation is better today. Most VoIP providers offer gateways to transfer calls to the 911 network, ensuring that calls do actually get answered. But unless the caller has previously updated his or her address, they won't necessarily be answered by the right PSAP.

"If you're sitting in Las Vegas, it will know to connect you through a gateway in Los Angeles," says Epler. This is because the network's own location data is based on the phone's IP address. While some IP blocks can be mapped to an exact address, most resolve to an ISP, whose router can be hundreds of miles from the caller.VoIP providers do have a way to provide full E-911 capability for users who have manually updated their location, but it isn't yet available nationwide. It requires support at the PSAP, and the local governments that run PSAPs often have other priorities than VoIP.

In theory E-911 over VoIP should require no changes to the 911 infrastructure, as it's designed to work in the same way as wireless E-911. When a customer moves, a dedicated positioning center finds the closest PSAP and then assigns the customer an Emergency Services Query Key (ESQK), a temporary phone number within the PSAP's geographic area (see "E-911 In a VoIP Network", above). The ESQK isn't known to the VoIP customer because it's only used for 911. The dedicated 911 network uses it to route calls to the appropriate PSAP, and then the PSAP itself uses it to retrieve the location from the ALI.

In practice, not every PSAP has upgraded its ALI to support wireless E-911 (see table). VoIP also faces an additional obstacle in the limited supply of ESQKs. Each area code contains only a finite number of phone numbers, most of which are needed for real phones. And whereas spectrum licensing means there are rarely more than four cellular operators competing for a PSAP's temporary numbers, the potential demand from VoIP is infinite.

FIXING A LOCATION

The long-term solution may be to move the location database out of the PSAP, making it the responsibility of whoever controls the physical network infrastructure. Many states are already making this mandatory for enterprise PBXs, and the FCC's proposed national rules require exact location information for any phone within a building with a total floor area of more than 7,000 square feet."If it's not a requirement now, it soon will be," says Richard Zimmerman, director of network solutions at Forsythe Technology, a VAR and consultancy. He designs VoIP systems for companies across the country and recommends that all of them install an E-911 system that can locate individual phones--in essence, they should have an in-house version of the ALI used in the public network.

Most of Zimmerman's customers are Cisco shops, so he uses Cisco's Emergency Responder software. But similar functionality is available for other IP PBXs, often through third-party software vendors. For example, Avaya has partnered with E-911 specialist RedSky Technologies, which also makes systems for old-fashioned TDM-based PBXs. Nortel Networks has partnered with Qovia, an IP telephony management company. All the software works in roughly the same way, providing a database that maps Ethernet switch ports to a physical location.

Populating the database can take some initial work, but once that's done everything is automatic. When an employee unplugs an IP phone and takes it into a conference room, the system will look at the Ethernet port, not just the phone itself, and so correctly locate the user. Because it's based on ports, not clients, it works just as well for a softphone running on a laptop--provided, of course, that the user remains within the enterprise network.

The databases can span multiple sites, so there's no problem when employees move between offices or cities. An executive based in San Francisco who visits her company's New York office will be able to make and receive calls through the San Francisco number, yet be correctly routed to a PSAP in Manhattan when dialing 911. However, there's a big problem when users try to access the IP telephony system from a home office or hotel, as the database can only cover the network's own switches.

"We can see that someone is tunneling through a VPN port, so we know they're not in the building," says Steve Mank, Qovia's COO. "But we don't know exactly where they are." As with VoIP services offered by external providers, users must update their locations manually.FINDING A SIGNAL

PBXs also have problems when internal users are running VoIP over an internal Wi-Fi network. Wi-Fi phones are still comparatively rare in most enterprises, but they're used extensively in a few niche industries. Among their largest users are hospitals, where the ability to locate a person or a piece of equipment can be critical.

If the PBX's database only includes Ethernet ports, it will only be able to tell which AP a user is connecting through, not exactly where the user is. In a dense network where every user connects through the closest AP, that may be enough. But the typical Wi-Fi AP has a range of about 340,000 square feet. That's nearly 50 times the area allowed by the FCC's proposed rules.

It's unlikely that any FCC rules governing enterprise PBXs will cover wireless VoIP. The state laws don't mention it at all, and there are already E-911 regulations for cell phones. These are comparatively lax by Wi-Fi standards: Networks that don't place a GPS receiver inside each phone need to get two-thirds of their location fixes right to within 150 meters, so just finding the nearest AP should be accurate enough.

Enterprises that require accurate location data from internal wireless devices need to consider other systems. The leading one for Wi-Fi networks is RF fingerprinting, also known as Wireless Location Signatures. RF fingerprinting measures the strength of a signal and compares it against a reference model. By understanding how radio waves are affected as they pass through and defract around different building materials, the network can calculate a position to within a few feet. The precise accuracy depends on the building's architecture--the more walls and immovable objects, the better--but it can generally determine which room a user is in.RF fingerprinting's earliest adopters were European cell phone operators. Many use a system from software company Polaris Wireless, which pitches it mainly as a management technology: Knowing where customers are helps carriers decide where to put more cell towers and allows them to bill based on location. Its initial applications in Wi-Fi were similar. For two years, Newbury Networks has been selling an overlay network of hardware sensors that use RF fingerprinting for security and management. For example, it can restrict coverage to particular areas or pinpoint intruders.

Wi-Fi vendors are now using the technology for more general location-based services. For example, Ekahau sells software that can add RF fingerprinting capability to standard IEEE 802.11 networks, tracking the locations of all users and storing them on a Windows or Linux server. Makers of Wi-Fi APs are also beginning to incorporate RF fingerprinting, as most already provide less accurate location databases. The first to market was Cisco, thanks to its acquisition of Airespace. It stores the tracked location data in a dedicated appliance, which applications can access through a SOAP interface.

Wi-Fi telephony is unlikely to become popular until dual-mode phones that also include cellular capability are available. This will give users another option for location tracking, as all cellular networks now need to incorporate positioning capability. The technologies they use often go beyond the FCC's requirements, though precision can vary widely. For example, the GPS receivers used by CDMA providers such as Sprint and Verizon tend to be much more accurate outside, but can be a problem in office environments.

Click here to read Andy Dornan's commentary or write to him at [email protected].

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