Carriers, PSAPs prepare for transition to VoLTE

As wireless carriers migrate their systems to 4G LTE—specifically, voice over LTE (VoLTE)—both carriers and public-safety answering points (PSAPs) will have to make adjustments to ensure that 911 service standards are maintained, according to an Intrado official.

“I see VoLTE as one of the biggest fundamental changes in the wireless industry in how they’re doing things—moreso than even going to digital,” said John Snapp, Intrado’s senior technical officer, during an interview with Urgent Communications.

“They’ve spent the last 20-something years working on optimizing the data path for voice over these separate channels. Now they’re saying, ‘We’re going to throw all of that away, start over from scratch and build the voice services using … a voice-over-IP implementation over this new LTE data network that we’re putting into place.’ That’s a really major change for them, and that’s not untouched with what’s happening with 911, too.”

Indeed, all of the location and switching elements used for 911 by existing 2G voice networks—still used for most commercial wireless voice, even where 3G technology is used for data—will be replaced by new IP-based elements for VoLTE, Snapp said.

This will work best when carriers have migrated fully to VoLTE and PSAPs have deployed next-generation 911 in an all-IP architecture that should be able to leverage modern technology to be more dependable, Snapp said.

“With VoLTE, as I make a 911 call to the police here, it could very likely go through New York before it comes back and hits the network,” he said. “So now, there can be a lot of aggregation of the traffic—the carriers have fewer connections, so the connections can be mad e more reliable.”

 “It’s now really becoming a national network—and a cloud-based network—instead of a bunch of little local networks that were plugged together.”

Of course, it is likely that carriers will migrate to VoLTE and PSAPs will migrate to i3 and next-gen architectures at different times. During this transition period that could last for several years, VoLTE carriers need to be able to communicate with legacy PSAPs, and next-gen PSAPs have to be able to accept calls from 2G networks. Snapp said that solutions exist from multiple vendors to allow this happen as seamlessly as possible.

“The lucky part is that the … way it’s being built, it’s going to be transparent to both sides—we’re really decoupling one side from having to worry about the other side upgrading,” Snapp said. “By doing this transitional interface, it insulates the carrier from having to worry too much about i3, and it insulates the PSAP from having to worry too much about LTE.”

“It’s a solution that we’re doing and other providers are doing also—it’s part of the i3 architecture. It’s what the carriers are having to put in place to communicate with legacy PSAPs. So, if the PSAP is not i3, we have to do this anyway to convert to them. If it’s an i3 network on the PSAP side, they have to put in this equipment to communicate with non-LTE wireless carriers, because we’re going to see a combination of VoLTE and circuit-switched for at least five years to come—so, they have to support both interfaces.”

Snapp said that he believes carriers have significant incentive to convince customers to migrate their voice services from 2G networks to the more spectrally-efficient LTE platform, so he believes that transition will occur for most carriers within the next few years. Trying to guess when PSAPs can move to a next-generation architecture is much tougher, because the fiscal realities dictate that many PSAPs are just trying to maintain existing systems and do not have additional funds to pay for NG-911 equipment.

According to Snapp, once the transitions to VoLTE and NG-911 are complete, the all-IP platform will allow the 911 system to leverage some powerful capabilities—for instance, improving location information when a wireless caller makes an emergency communication via the 911 system.

“With original 911 VoIP, there was always the hope that they would make these location services that could be utilized for commercial location services, but that wasn’t really realized with the original 911,” Snapp said. “They built 911 location for 911 VoIP, and they built a completely separate network for commercial location, and they didn’t utilize the same components.

“Now, what’s being done in VoLTE, commercial location and 911 location are one and the same in the technologies and standards they use. Now, 911 won’t be this not-quite-as-used one off; it’s going to be used for commercial [location services]. So, the accuracies that you get in commercial location and the advances in technology can be quickly brought into 911.”