In a world of ubiquitous multimedia connectivity with Snapchat, Twitter, Skype - pick your favorite communication app - most people take access to communication services for granted. In fact, universal service - the principle that all consumers should have access to communications services - was first publicly proclaimed in 1907 by AT&T’s then president, and made law in the US with the Communications Act in 1934. Unfortunately for millions of hearing impaired consumers, this concept was not realized until the mid 1960s. In 1964 Ma Bell’s PSTN added a second sense with the introduction of Telecommunications Devices for the Deaf (TDDs).
TTY – What Is It?
Simply put, a TDD is a teletype (TTY) device - a phone with a keyboard and screen. These devices weren’t just an on ramp to the telephone network. They became a lifeline when 1991’s Americans with Disabilities Act mandated that emergency 911 service call centers support TTY users.
Tools and technology for remote communication for the hearing impaired have come a long way. Instant messaging, video calling, and Real Time Text (RTT), the IP successor to TTY, have overcome many of the limitations of TDD, including the fact that TTY users can only communicate with other TTY users. Not surprisingly, TTY use has declined dramatically: In August of 2008, carriers handled over 787,000 minutes of interstate TTY-based calls. This dropped by over 50% by August 2012, to 352,000 minutes, and by more than half again to 156,000 monthly minutes in August 2015.
Based on these factors, in 2015 AT&T successfully petitioned the Federal Communications Commission (FCC) to waive the requirement to support TTY in wireless IP networks, albeit on a temporary basis. In February of this year, the ruling became permanent (Document FCC 16-169). Wireless IP network operators can now deploy RTT services in lieu of TTY. At the same time, the commission recognized that a community of users dependent on TTY still exists. And in a renewed validation of the fundamental obligation of operators to extend universal access, the FCC ruling mandated that wireless IP networks must support interoperability between RTT and TTY users with no defined expiration for this requirement. In defining potential technology solutions, the commission identified transcoding as one of the cost-effective techniques for bridging the installed TTY base to RTT users.
As they are capitalizing on new technology for improving TTY without leaving its users behind, operators can also use this opportunity to improve on their approach to transcoding. They can overcome the limitations of traditional transcoding devices like SBCs and Media Gateways (MGW) for enabling transcoding with the use of Media Resource Function (MRF) and Transcoding Resource Function (TRF) elements in their IP networks.
Delivering a Solution with a Compelling ROI
As IP to PSTN text transcoding is a relatively low volume case, many existing SBC and MGWs do not even support the functionality. But even when they do, the alternative approach offers operators a more compelling return on investment in just about any contemporary transcoding use case.
Why? Because the technology scales independently of signaling for more cost-effective multimedia transcoding (text, voice and video) while preserving the existing SBC or MGW infrastructure.
For example, as the EVS codec becomes more widely adopted in new VoLTE terminals, the acquisition cost of transcoding using network MRF or TRF elements typically saves 50 to 60% of the cost of expanding existing SBC and MGW infrastructure. The savings are compounded by lower ongoing opex costs based on a footprint that requires two-thirds of the data center space and correspondingly lower power, cooling and management demands. And it represents a future proof solution that can be used for transcoding of future codecs while serving the media features of other services as TTY use continues its decline to inevitable obsolescence.
Radisys MediaEngine virtual and NFV-accelerated MRF and TRF platforms are already widely deployed as the media processor in dozens of mobile IP networks around the world, including two tier-one carriers in North America for text transcoding. With simple software upgrades they can support the latest codecs for text, EVS, and video transcoding. And via a variety of interworking options, can be seamlessly integrated with existing SBCs, MGWs, CSCFs or other call routing engine (CRE) elements to optimize utilization of the combination of existing SBC/MGW and new MRF/TRF capacity.
For more information about Radisys transcoding solutions, please email open@radisys.com.
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