Access for 9-1-1 and Telephone Emergency Services

C. Other Requirements for TTY Equipment

Maintenance and Back-Up

The ADA regulation contains a specific provision requiring that covered entities maintain their accessibility features and equipment in operable working condition. In addition to this specific maintenance requirement, the ADA's equal access requirement obligates PSAPs to implement equally effective procedures for maintenance and back-up capability for TTY equipment as they provide for voice telephone equipment. For example:

TTY equipment must be maintained and tested at least as often as voice telephone equipment, to ensure that the equipment is operating properly. If PSAPs check their voice telephone equipment every day to make sure it is working, they must do so every day for TTY equipment. Similarly, if PSAPs have contracts with outside companies for maintenance of their voice telephone equipment, they must employ equally effective methods for TTY equipment. Most PSAPs have plans for using back-up equipment in case some of its equipment or telephone lines malfunction, or in case there is a power failure. If a PSAP has such a plan for voice calls and equipment, it must provide for TTY calls and equipment in that plan. For instance, PSAPs should keep extra TTY equipment on hand, in case the primary equipment fails, if they have back-up voice telephone equipment for such a situation.

Switching Between Voice and TTY Modes

All call takers must have the capability to switch back and forth easily from TTY mode to voice mode during the same call. This capability is necessary especially for silent calls, since call takers are required to first query the line by voice and then quickly switch to query the line by TTY. This capability is also necessary for VCO and HCO, which are described below. VCO and HCO shorten the lengths of calls that would otherwise be conducted exclusively by typing. Call takers who use stand-alone TTYs can switch from TTY mode back to voice mode simply by removing the telephone handset from the TTY couplers. TTY-compatible consoles for call takers should have built-in switching capability.

Q: What is VCO? Who uses it?

A: VCO is voice carryover. It is a communication hybrid of TTY and voice. VCO allows a person with hearing loss to speak directly to the call taker and read the response that is typed back. Many persons who became deaf or hard of hearing later in life prefer to speak instead of type. They use what is called voice carryover (VCO). With VCO, the caller speaks directly into the phone, and the call taker types back via TTY to the caller. VCO can be accomplished with standard stand-alone TTY equipment simply by having the call taker alternate between listening on the handset when the caller is speaking and placing the handset in the TTY couplers to type a response.

Q: What is HCO? Who uses it?

A: HCO is hearing carryover. People with speech impairments who are not deaf or hard of hearing often prefer HCO. HCO allows them to type their words on a TTY to call takers and hear call takers' spoken responses through their handset. HCO can be accomplished by a call taker using standard stand-alone TTY equipment by alternating speaking into the handset and placing the handset in the TTY when the caller types a response.