Phone with Girl Waving

T-Mobile accessibility

T-Mobile is committed to providing products and services that meet a variety of communication needs.

Accessibility support

T-Mobile will provide accessible support for wireless network service and billing inquiries. Please contact our Accessibility Customer Care at 1-833-428-1785 if you have any questions or need special assistance. For additional support, please contact Customer Care.

For media requests, commercial questions, or customer service inquiries, visit our visit our Contact Us page.

We’re proud to be one of the best places to work for employees with disabilities since 2018.

Diversity and inclusion make us who we are. That’s why we’re proud to be a top-scorer on the 2022 Disability Equality Index, making us one of the best places to work for employees with disabilities for the fifth year in a row. In addition, T-Mobile has been named Disability:In's Employer of the Year for 2022, solidifying our commitment to the accessibility community.

We’re offering devices with you in mind

T-Mobile offers accessible services and device options supported by the following operating systems.

Visual

Alternate billing options

T-Mobile's billing statements are provided online at my.t-mobile.com and are accessible to the visually impaired using readily available reading programs. T-Mobile also offers alternate printed billing options. For more information please contact Accessibility Customer Care at 1-833-428-1785.

Directory Assistance Program

Our Directory Assistance Program helps provide greater access to 411 information services for customers with visual, physical and/or cognitive disabilities by offering credits for such services. For instructions on how to apply for the Directory Assistance Program, download the Directory Assistance Exemption Form: T-Mobile 411 Accessibility Form

For more information about the Directory Assistance Program or other accessibility benefits T-Mobile offers, our Customer Care department is available to assist you. Customer Care is available between 6:00 a.m. -11:00 p.m. CT, Monday through Friday, you can also email access@t-mobile.com. Toll free at 1-833-428-1785.

Speech

RTT

Real-Time Text (RTT) provides an alternate way of meeting the communication needs of consumers with disabilities. It provides a more instant transmission and delivery of a message as it is being composed, making it more equivalent to a typical voice conversation. For example, the user may be able to see partial responses and develop a response before the entire message is complete. This can help reduce crossed answers and better connect emergency 911 services in supporting locations.

For more information on the benefits of Real-Time Text and the adoption of RTT rules by the FCC, visit FCC RTT Rules Adoption.

Text–to-911 service

Users may be able to reach emergency services by sending an SMS text message to 911 from their mobile phones or devices, depending on where they reside. You will receive a bounce-back message if 911 text service is not available. When possible, the FCC encourages users to first contact 911 via voice call because text-to-911 is not available everywhere.

For more information on text-to-911 service by the FCC and what locations the service is available in, visit FCC Text to 911: What You Need To Know.

Seniors

Easy-to-use handsets

T-Mobile offers a wide range of handsets to meet seniors' needs. From flip phones to affordable smartphones and premium phones, T-Mobile can help you find the right phone for you.

For more information check out T-Mobile phones.

Alternate billing options

T-Mobile's billing statements are provided online at my.t-mobile.com and are accessible to the visually impaired using readily available reading programs. T-Mobile also offers alternate printed billing options. For more information, please contact Accessibility Customer Care at 1-833-428-1785.

T-Mobile Location Services

T-Mobile offers products that can help monitor your location and safety and keep tabs on your family. For more information about products that support location services, visit T-Mobile SyncUP DRIVE.

Virtual personal assistants

There are several virtual personal assistants available on today’s mobile devices that work hard to make life easier.

Auditory

Hearing aid compatibility

T-Mobile ensures that a certain portion of its essential handsets offered to customers are compatible with hearing aids.

Some hearing aid users may detect interference in the form of a buzzing, humming, or whining noise when using a wireless phone. The amount of interference experienced may vary due to differences in immunity levels of hearing aids.

A rating system (M1 through M4 for microphone and T1 through T4 for telecoil) is used to assist consumers with identifying handsets designed to be compatible with hearing aids. Federal Communications Commission (FCC) rules require the labeling of phones that receive a rating of 3 or 4, which are deemed to be hearing aid compatible. Phones that receive a rating of 3 or 4 usually cause the least amount of interference. Typically, the higher the M or T rating assigned to a phone, the less interference.

Although the rating system is not a guarantee, it is a useful tool for consumers to determine the most appropriate wireless handset.

For additional information about hearing aid compatibility with digital wireless phones, see the hearing aid compatibility brochure and the FCC guide.

Important note about HAC phones

Hearing-aid-compatible phones have been tested and rated for use with hearing aids for some of the wireless technologies they use. However, some newer wireless technologies used in these phones may not been tested yet for use with hearing aids. It is important to try the features of your phone thoroughly and in different locations, using your hearing aid or cochlear implant, to determine if you hear any interfering noise. Consult the manufacturer of your phone for information on hearing aid compatibility. If you have questions about return or exchange policies, consult your service provider or phone retailer.

Handsets with Wi-Fi or Voice over LTE (VoLTE) calling capabilities may not have been tested for hearing aid compatibility in these calling modes.

HAC phones and ratings

Hearing Aid Compatible Phones
T-Mobile currently offers the following hearing- aid-compatible handsets—all rated at M3 or better. Any handset rated M3 or better (as well as T3 or better) was evaluated using the 2011 ANSI Standard.

Best/Premium: Devices featuring higher-end design, materials, and finishes, paired-up with a more sophisticated user interfaces and functionalities.

Apple iPhone 15 (rated M3 & T4) (FCC ID - BCG-E8427A)
Apple iPhone 15 Plus (rated M3 & T4) (FCC ID - BCG-E8431A)
Apple iPhone 15 Pro (rated M3 & T4) (FCC ID - BCG-E8435A)
Apple iPhone 15 Pro Max (rated M3 & T4) (FCC ID - BCG-E8439A)
Apple iPhone 14 (rated M3 & T4) (FCC ID - BCG-E8138A)
Apple iPhone 14 Plus (rated M3 & T4) (FCC ID - BCG-E8139A)
Apple iPhone 13 mini (rated M3 & T4) (FCC ID - BCG-E3994A)
Apple iPhone 13 (rated M3 & T4) (FCC ID - BCG-E3997A)
Apple iPhone SE (3rd gen) (rated M3 & T4) (FCC ID - BCG-E4082A)
Google Pixel 8 -  FCC ID - A4RG9BQD - M3 & T4
Google Pixel 8 Pro - FCC ID - A4RG1MNW - M3 & T4
Google Pixel 7a (rated M3 & T4) (FCC ID: A4RGWKK3)
Google Pixel 7 (rated M3 & T4) (FCC ID: A4RGQML3)
Motorola edge 2022 (rated M3 & T3) (FCC ID: IHDT56AE7)
Motorola razr+ 2023 (rated M3 & T3) (FCC ID: IHDT56AJ3)
Motorola razr 2023 (rated M3 & T3) (FCC ID: IHDT56AL9)
Samsung Galaxy S24 (rated M3 & T3) (FCC ID: A3LSMS921U)
Samsung Galaxy S24+ (rated M3 & T3) (FCC ID: A3LSMS926U)
Samsung Galaxy S24 Ultra (rated M3 & T3) (FCC ID: A3LSMS928U)
Samsung Galaxy S23 (rated M3 & T3) (FCC ID: A3LSMS911U)
Samsung Galaxy S23+ (rated M3 & T3) (FCC ID: A3LSMS916U)
Samsung Galaxy S23 Ultra (rated M3 & T3) (FCC ID: A3LSMS918U)
Samsung Galaxy S22 (rated M3 & T3) (FCC ID: A3LSMS901U)
Samsung Galaxy Z Flip3 (rated M3 & T3) (FCC ID: A3LSMF711U)
Samsung Galaxy Z Flip5 (rated M3 & T3) (FCC ID: A3LSMF731U)
Samsung Galaxy Z Fold5 (rated M3 & T3) (FCC ID: A3LSMF946U)
Samsung Galaxy S23 FE (rated M3 & T3) (FCC ID: A3LSMS711U)

 

Good: Entry-level phones with straight-forward features, applications, and designs.

Motorola moto g 5G - 2023 (rated M3 & T3) (FCC ID IHDT56AH4)
Motorola moto g stylus 5G - 2023 (rated M3 & T3) (FCC ID: IHDT56AL2)
Nokia G310 5G (rated M4 & T3) (FCC ID: 2AJOTTA-1573)
OnePlus Nord N30 5G (rated M2 & T2) (FCC ID: 2ABZ2-AA534)
Samsung Galaxy A15 5G (rated M3 & T3) (FCC ID: A3LSMA156U)
Samsung Galaxy A54 5G (rated M3 & T3) (FCC ID: A3LSMA546U)
Sonim XP3plus (rated M4 & T4) (FCC ID: WYPP14303)
Sonim XP3plus Non-Camera Version (rated M4 & T4) (FCC ID: WYPP14303)
TCL 30 XE 5G (rated M3 & T3) (FCC ID: 2ACCJH155)
TCL FLIP Go (rated M4 & T4) (FCC ID: 2ACCJN059)
TCL Stylus 5G (rated M3 & T3) (FCC ID: 2ACCJN058)
T-Mobile® REVVL® 6x 5G (rated M3 & T3) (FCC ID: 2APXW-TMRV065G)
T-Mobile® REVVL® 6x PRO 5G (rated M3 & T3) (FCC ID: 2APXW-TMAF035G)
T-Mobile® REVVL® 6 5G (rated M3 & T3) (FCC ID: 2APXW-TMAF025G)
T-Mobile® REVVL® 6 PRO 5G (rated M3 & T3) (FCC ID: 2APXW-TMAF035G)

Last updated on 3/6/24

For more information about phone accessibility features, as well as information about current and older phones, visit the Global Accessibility Reporting Initiative's website at www.gari.info.

For more information about hearing aid-compatible phones, please contact Customer Service.

T-Mobile USA, Inc. has a limited phone exchange, return, and upgrade opportunity for hearing-aid-compatible phones that are used by customers meeting certain restrictions. Customers are limited to 14 days for purchases from a T-Mobile retail location and 20 days for purchases made online or over the phone. For additional information, please contact T-Mobile at 1-800-937-8997 or via TTY Customer Care at 1-877-296-1018 (TTY hours: 5:00 a.m. – 10:00 p.m. PT, daily).

Mobile text telephone (TTY)

Telecommunications Relay Services
Telecommunications Relay Service (TRS or “relay service”) is a communication service that permits individuals with a hearing or speech disability to use the telephone system via a TTY, or other device, to call persons with or without such disabilities through a TRS relay center.
Different forms of relay service include Text-to-Voice TTY, Voice Carry Over (VCO), Hearing Carry Over (HCO), Speech-to-Speech (STS), Spanish Text-to-Voice TTY, Captioned Telephone, IP Captioned Telephone, IP Relay, and Video Relay Service (VRS). More information about the available types of relay service can be found on the FCC’s TRS website.

TRS is available in all 50 states and all U.S. territories for local and long-distance calls. TRS providers are compensated for the costs of providing TRS from either a state or a federal fund, and there is no charge to the TRS user other than standard calling rates.

Relay service can be reached by dialing 711 or by contacting your state relay provider, as listed in the FCC’s TRS Directory. In the event of an emergency, TTY users should call 911 directly.

T-Mobile TTY policy

A TTY, also known as a Text Telephone Device or Telecommunication Device for the Deaf (TDD), is a special device that enables people who are deaf, hard of hearing, or speech-impaired to use the telephone to communicate. TTY works by allowing people to type messages back and forth to one another instead of talking and listening. The device is required at both ends of the conversation.

The FCC requires digital wireless carriers to have the capability to transmit a call from a wireless phone that is connected to a TTY. While the FCC mandate pertains specifically to calls made to 911, the ability to make a call to 911 means users can also complete a call to anyone, anywhere, provided the party on the receiving end of the call also has a TTY.

TTY on T-Mobile's network
T-Mobile’s higher speed data services, including LTE, support use of IP-based TRS, including Video Relay Service, IP Relay, and IP Captioned Telephone Service through providers of those relay services. T-Mobile recommends use of these relay services as the most effective means of placing assisted calls, including to 911. If a T-Mobile customer nonetheless wants to use a mobile TTY, T-Mobile's GSM and UMTS cellular network is TTY compatible and may be used to reach 911. All T-Mobile price plans and most handset features will work with TTY. Customers will need to visit a T-Mobile retail store or contact Customer Service for assistance with selecting the proper rate plan and service activation.

Customers should be aware that TTY does not work on voice calls that are placed over Wi-Fi or Voice over LTE (VoLTE) at this time. This means that TTY calls, including TTY calls to 911, cannot be made while using IP-based calling, including Wi-Fi Calling and Voice over LTE. Customers with communications disabilities who need to call 911 while using IP-based calling should use IP Relay, Video Relay, or IP Captioned Telephone Service to reach emergency personnel. Where available, customers may also send a text message to 911 directly (text-to-911).

For more information, please view this short video about TTY on T-Mobile's network.

Closed captioning

Closed captioning contact information

If you receive IP-delivered video from T-Mobile TV and have questions, concerns or a complaint, please contact us by writing to:

T-Mobile Closed Captioning
ATTN: T. Shwonek, Legal Affairs
12920 S.E. 38th Street
Bellevue, WA 98006

Tel: 425-383-4000
Fax: 425-383-4030
Email: ClosedCaptioning@T-Mobile.com

For information on resolving disputes with T-Mobile, please review our Terms and Conditions under the heading “Dispute Resolution and Arbitration.” For additional information about closed captioning, see the FCC Guide.

RTT devices & availability

Real-time text (RTT) allows consumers to send and receive instant transmission of text messages as they are being composed, making these messages more equivalent to typical voice conversations. RTT also allows voice communication at the same time as text communication (simultaneous voice and text).

T-Mobile customers using Voice over LTE (VoLTE) or Wi-Fi Calling on RTT-enabled devices are able to send and receive RTT calls with other T-Mobile customers who are also using VoLTE or Wi-Fi Calling using RTT-enabled devices, as well as to subscribers of other carriers that support RTT. A list of T-Mobile's RTT device offering can be found below.

Apple iPhone 15
Apple iPhone 15 Plus
Apple iPhone 15 Pro
Apple iPhone 15 Pro Max
Samsung Galaxy Z Fold 5
Samsung Galaxy Z Flip 5
Samsung Galaxy Z Flip 3 5G
Motorola moto g 5G 2023
Nokia G310 5G
TCL Flip Go
T-Mobile® REVVL 6X
T-Mobile® REVVL 6X PRO
Apple iPhone 14
Apple iPhone 14 Plus
Google Pixel 8
Google Pixel 8 Pro
Google Pixel 7a
Google Pixel 7
Apple iPhone SE (3rd gen)
Apple iPhone 13 mini
Apple iPhone 13
Motorola edge 2022
Motorola moto g stylus 5G - 2023
Motorola razr+ 2023
OnePlus Nord N30 5G
Samsung Galaxy A54 5G
Samsung Galaxy A15 5G
Samsung Galaxy S22
Samsung Galaxy S23
Samsung Galaxy S23+
Samsung Galaxy S23 Ultra
Samsung Galaxy S23 FE
Samsung Galaxy S24
Samsung Galaxy S24+
Samsung Galaxy S24 Ultra
Sonim XP3plus
Sonim XP3plus Non-Camera Version
TCL 30 XE 5G
TCL Stylus 5G
T-Mobile® REVVL® 6 5G
T-Mobile® REVVL® 6 PRO 5G

The following devices are no longer sold, but are supported:

Apple iPhone 14 Pro Max

Samsung Galaxy A14

Samsung Galaxy A03s

Samsung Galaxy S21 FE 5G

Apple iPhone 14 Pro

Apple iPhone 13 Pro

Google Pixel 6

OnePlus 9 5G

OnePlus 10T 5G

Nokia G400 5G

Samsung Galaxy A23 5G

Apple iPhone 12

Samsung Galaxy S22+

Samsung Galaxy S22 Ultra

T-Mobile® REVVL 4

T-Mobile® REVVL 4+

T-Mobile® REVVL 5G

T-Mobile REVVLRY™

SCHOK Flip

Samsung Galaxy Z Fold2 5G

Samsung Galaxy Z Fold4

Samsung Galaxy Z Fold3 5G

Samsung Galaxy Z Flip 5G

Samsung Galaxy Z Flip4

Samsung Galaxy Note20 5G

Samsung Galaxy Note20 Ultra 5G

Samsung Galaxy S22 Ultra 5G

Samsung Galaxy S22 + 5G

Samsung Galaxy S20 5G

Samsung Galaxy S20+ 5G

Samsung Galaxy S20 Ultra 5G

Samsung Galaxy S21 5G

Samsung Galaxy S21+ 5G

Samsung Galaxy S21 Ultra 5G

Samsung Galaxy A71 5G

Samsung Galaxy A51 5G

Samsung Galaxy A52 5G

Samsung Galaxy A32 5G

Samsung Galaxy A10e

Samsung Galaxy A11

Samsung Galaxy A12

Samsung Galaxy A13 5G

Samsung Galaxy A21

OnePlus Nord N100

OnePlus Nord N10 5G

OnePlus Nord N20 5G

OnePlus Nord N300 5G

OnePlus 8T+ 5G

OnePlus 9 Pro 5G

Nokia X100

Motorola moto g play

Motorola one 5G ace

Motorola moto e

Motorola moto g 5G

Motorola moto g stylus 5G (2022)

LG WING™ 5G

LG Aristo® 5

LG G8 ThinQ™

LG K51™

LG Stylo™ 6

LG V60 ThinQ™ 5G

LG VELVET™ 5G

Google Pixel 3a

Google Pixel 3a XL

Google Pixel 6a

Google Pixel 4a (5G)

Google Pixel Fold

Alcatel GO FLIP 3

Apple Watch Series 3 38mm

Apple Watch Series 3 42mm

Apple Watch Series 5 40mm

Apple Watch Series 5 44mm

Apple iPad Pro 12.9-inch (3rd Gen)

Apple iPad (7th Gen)

Apple iPad Air (3rd Gen)

Apple iPad mini (5th Gen)

Apple iPhone 13 Pro Max

Apple iPhone 12 mini

Apple iPhone 12 Pro Max

Apple iPhone XS Max

Apple iPhone 11

Apple iPhone 11 Pro Max

Apple iPhone XR

Apple iPhone 8 Plus

Apple iPad (5th Gen)

Apple iPad (6th Gen)

Apple iPad Air

Apple iPad Air 2

Apple iPad Mini 2

Apple iPad Mini 3

Apple iPad Mini 4

Apple iPad Pro

Apple iPad Pro 10.5-inch

Apple iPad Pro 12.9-inch (2nd Gen)

Apple iPad Pro 9.7-inch

Apple iPhone 6

Apple iPhone 6 Plus

Apple iPhone 6S

Apple iPhone 6S Plus

Apple iPhone 7

Apple iPhone 7 Plus

Apple iPhone 8

Apple iPhone SE

Apple iPhone X

Apple iPhone XS

Coolpad Snap

Google Pixel 3

Google Pixel 3 XL

Google Pixel 4

Google Pixel 4 XL

LG Aristo 2 Plus

LG Aristo 4+

LG G6

LG K30

LG K40

LG G7 ThinQ™

LG Q7+™

LG Stylo 4

LG Stylo™ 5

LG V40 ThinQ™

Motorola moto e 6th Gen

Motorola moto g7 power

OnePlus 6T

OnePlus 7 Pro

OnePlus 7T

OnePlus 7T Pro 5G McLaren

Samsung Galaxy A6

Samsung Galaxy A20

Samsung Galaxy J3 Star

Samsung Galaxy J3 Star - Certified Pre-Owned

Samsung Galaxy J7 Prime

Samsung Galaxy J7 Star

Samsung Galaxy Note 8

Samsung Galaxy Note9

Samsung Galaxy Note10

Samsung Galaxy Note10+

Samsung Galaxy Note10+ 5G

Samsung Galaxy S7

Samsung Galaxy S7 Edge

Samsung Galaxy S8

Samsung Galaxy S8 Active

Samsung Galaxy S8+

Samsung Galaxy S9

Samsung Galaxy S9+

Samsung Galaxy S10

Samsung Galaxy S10e

Samsung Galaxy S10 5G

Samsung Galaxy S10+

T-Mobile REVVL 2

T-Mobile REVVL 2 Plus

T-Mobile REVVLRY+™

Wiko Voix

 

What is RTT?

Real-time text, or RTT, is a communication protocol that allows users who are deaf, hearing impaired or have speech disabilities to send and receive textual messages in real time. Characters are sent as they are typed, allowing the other party to see a message as it is being written. Unlike other types of texting methods, RTT is similar to a voice call – when you place an RTT call, the other party must answer the call, and when the call is over, both parties hang up.

Why is T-Mobile offering RTT?

RTT is a replacement for an older technology that uses teletypewriter devices, or TTYs, to send and receive textual messages during a phone call. TTYs are mostly special telephones connected to old phone networks. RTT uses IP network technology that may provide improved reliability, accuracy, and speed. RTT also has increased functionality, such as an expanded character set, and offers the ability to use talk and text at the same time. Accordingly, RTT may provide a better way of communicating with text for consumers that need to communicate in real-time using text.

How is RTT different from SMS or MMS?

SMS (short message service) and MMS (multimedia message service) are “best effort” services, meaning that messages are not always received immediately, and sometimes messages are received out of order. RTT, on the other hand, is like a voice call – when you place an RTT call, the other party must answer the call, and when the call is over, both parties hang up. While RTT is designed to allow simultaneous voice and text, RTT calls to a TTY device may not have simultaneous voice calling available. In addition, group or conference calling is not currently available with RTT.

Who can use RTT?

T-Mobile customers, including customers who are deaf, hearing impaired or have speech disabilities, using VoLTE or Wi-Fi Calling and using an RTT-enabled device are able to send and receive RTT calls with other T-Mobile customers on VoLTE or Wi-Fi Calling who are using capable devices. In addition, T-Mobile customers are able to make RTT calls to and receive such calls from other carriers’ subscribers who are able to make and receive RTT calls. RTT technology is still relatively new, with some of the smaller carriers just beginning to deploy the service. Therefore, RTT calling may not work as expected if you are roaming on another carrier’s network or if you are roaming on a network that does not support VoLTE. RTT will not work on T-Mobile's 2G and 3G networks. Roaming customers who are able to make VoLTE calls may be able to make RTT calls, depending on the roaming network.

RTT calling

What Type of Service Plan will I need?

T-Mobile customers on voice plans will be able to take advantage of RTT on their RTT-enabled device. RTT is only available when a voice call is placed or received on an RTT-enabled device. If you have a data only plan and would like to use RTT, you will need to switch to a voice plan. A voice plan is required because RTT technology requires voice call functionality in order to work. To change your plan or obtain more information on which plans and devices are required for RTT, please contact T-Mobile's Accessibility Queue at 1-844-375-8107.

Can I make an RTT call to someone who is not a T-Mobile subscriber?

Maybe. Not all carriers have deployed RTT. In addition, RTT is not supported on older 2G and 3G networks.

Can I use RTT if I am roaming on another network?

Maybe. If you are roaming on a network that supports VoLTE and RTT, you should be able to make RTT calls while roaming. Not all wireless carriers have rolled out RTT yet, and not all LTE networks support VoLTE. If you are roaming on a network that does not support VoLTE or RTT calling, you will not be able to make RTT calls.

Can I make RTT calls from my tablet?

For a list of T-Mobile’s RTT device offering, including tablets, view the “RTT devices & availability” FAQ on this page.

RTT to TTY

Consumers can also use RTT to communicate with people using legacy teletypewriters, or TTY devices, on legacy networks. Note that RTT supports additional characters that may not be available on TTY. And because TTY is an older technology, TTY users have developed etiquette regarding how to signal when a message is complete, when to pause and wait for a reply, and when to end a call. RTT users may not be aware of this etiquette. If you are not sure how to use RTT when interacting with TTY users, or if you experience difficulty making an RTT call to a recipient using TTY, consider using an alternative communication method.

How would a person become familiar with TTY etiquette?

TTY etiquette describes a general communication style that is oftentimes applied by persons using TTY-oriented equipment. There are several online references currently available (e.g., etiquette guides and glossaries) that describe some of the shorthand references and techniques used by individuals to help more effectively “speak” during a TTY session.

RTT to 911

RTT calls to 911 may be answered by emergency services personnel using TTY devices. Consumers using RTT to contact 911 should be aware of the differences between RTT and TTY, including how certain characters are translated between the two and that emergency responders who answer the call are likely to use TTY etiquette in their responses. If you experience difficulty making an RTT 911 call, you may want to try an alternative means of reaching 911, including making a voice call.

RTT to RTT

T-Mobile customers with RTT-enabled devices will be able to send and receive RTT calls with other T-Mobile customers who have RTT-enabled devices. This functionality is available when the underlying network is 4G LTE (VoLTE) capable or Wi-Fi calling has been enabled. RTT will not function in the 2G/3G network. As inter-carrier RTT networks becomes operational, T-Mobile subscribers will also be able to send and receive RTT calls with subscribers of other carriers that support RTT functionality.