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Wireless Telephones and TTYs - September, 2002


The wireless telephone industry has been working for several years to make mobile networks and handsets compatible with TTYs. The TTY industry has also made changes to selected models of TTYs to ensure that the system would work well for consumers. The requirement to make wireless telephones compatible with TTYs was an FCC rule, issued originally in 1996, on enhancing 9-1-1 services to citizens by making better use of the wireless networks.

Service Providers

The largest service providers have completed the implementation of TTY compatibility in their networks. AT&T Wireless Systems, Cingular Wireless, NexTel, Sprint PCS, T-Mobile (formerly Voicestream), and Verizon Wireless have completed their work. There may be a few areas of some of these networks that remain incompatible in the fall of 2002, but the full networks of these large service providers should be completed by the end of the year.


Wireless Phones

Each service provider allows certain handsets (phones) to be used with their networks. At first, not all of these handsets will work with TTY but over the next year or so, most or all handsets will probably work with TTY.

To use a handset with a TTY, the user must put the handset into TTY mode using the phone's menus. (This is a process similar to turning on closed captions on a TV set.) Usually this item can be found under “settings” or “set-up” or “profile.” The TTY setting may be in a sub-menu, sometimes under “miscellaneous”, “headset,” or “extras.” On most phones, once the phone is set in TTY mode, it will stay there until the user changes it.

VCO will have a separate menu item if it is supported. On some handsets, when the phone is in VCO mode, no TTY signals will go out. Thus some handsets will require VCO users to start in TTY mode for contacting the relay service and then push a button or two to change from TTY mode to VCO mode.

After setting the phone for TTY mode, the user then plugs the TTY cable into the headset (audio) jack on the wireless phone. This is a specialized cable (“TSB-121 Compliant”). The handset is used to dial the number.

Deaf and hard of hearing users should look for a phone with a vibrating feature, or one that works with a vibrating accessory, for detecting incoming calls. Most phones will provide a ”missed call” text notification if the user missed an incoming call, and what number was calling.



Not all TTYs will work with digital wireless phones. They must have an audio jack and must conform to certain technical standards. TTY manufacturers and distributors can help identify which TTY to select. You will receive a cable that must be used with that TTY. TTYs built for use with wireless phones are made by Ultratec, Inc., Ameriphone, Inc., and DSPG, Ltd, whose product is sold in the U.S. by Hi-Tec Group International. TTYs that are compatible with digital wireless phones may show the symbol shown below.

Symbol of TTY and Cellphone

It is probably a good idea to pick the TTY first, and then take it to a store operated by the wireless service provider. This way the phone can be tested with TTY before purchase of the phone and service.

Ultratec customers will find that the mobile TTY (Compact C) will be set to Baudot, not to TurboCode. This is because wireless phones do not necessarily work with TurboCode.

Problems with 9-1-1?

The wireless industry tested their phones and networks with TTYs. Among the tests were wireless TTY calls to 9-1-1 equipment. They found more garbling when calling these devices than in other situations. Unfortunately it is not possible to know whether a call to 9-1-1 cal via TTY will be successful. This is a problem that needs to be solved, but it is impossible for consumers to verify compatibility, because it is not legal to make test calls to 9-1-1.

However, the industry is under government order to make it possible – in the future -- for 9-1-1 services to locate wireless-telephone consumers who dial 9-1-1, even if the service is unable to communicate with them directly.


Consumer Tips

If you experience garbling, you can try several things to improve the situation:

  • Check that the connecting cable is firmly plugged in to both the TTY and the handset.
  • Rotate the phone so that the signal is as strong as possible (more “bars” means a stronger signal);
  • Move the phone away from the TTY as far as the cable will extend; turn the phone face down
  • Move to another location and try again. Weak signal strength will cause garbling and dropped calls.

Some phones show on their display whether the phone is already set to TTY mode. Usually this symbol is not displayed unless the connecting cable is plugged in to the handset. For example, Panasonic handsets with TTY feature will show the letter T on the display while the phone is in TTY mode. This is a good feature to look for.

Before buying a phone, check to make sure the TTY mode stays on, even if you turn off the phone and then turn it on and place another call.

Find out whether the voicemail system works with TTY. If it does not, you may want to disable voicemail on your phone. You may need help at the service provider’s store with this. Alternatively, you could have TRS type your voice messages (again, TTY messages may not record well). Some voicemail systems, though, can only be accessed by dialing within the wireless network, so TRS could not get into your mailbox. In these cases, disabling voice mail may be your best solution.

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