TL;DR
- Relay UK is the national text relay service allowing deaf and speech-impaired people to communicate with hearing people via phone calls.
- It works through the free Relay UK app or by dialling 18001 (to call someone) or 18002 (to receive calls); a trained relay assistant converts text to speech and vice versa.
- Ofcom requires all UK mobile and landline providers to offer access to the text relay service under the Communications Act 2003 and associated general conditions.
- The service is available 24 hours a day, 365 days a year; calls made through Relay UK count against any inclusive call allowance on your plan.
- BT operates Relay UK under contract; the app is available on iOS and Android and requires no special hardware beyond a smartphone.
What Relay UK Is and Why It Exists
Relay UK is the text relay service for the United Kingdom, enabling people who are deaf, deafblind, hard of hearing, or have a speech impairment to make and receive telephone calls with hearing people who may have no specialist equipment at all. A trained relay assistant sits between the two callers: they read aloud the text typed by the deaf or speech-impaired caller to the hearing person, and they type back everything the hearing person says so that it appears on the deaf or speech-impaired caller's screen in real time.
The service exists because telephone communication has historically been inaccessible to a significant portion of the population. Ofcom's regulatory framework, grounded in the Communications Act 2003 and the general conditions of entitlement it enforces, requires all providers of publicly available telephone services to ensure their customers can access text relay. BT currently operates the Relay UK infrastructure under contractual arrangement. The service replaced the older Next Generation Text (NGT) service and its predecessor Typetalk, carrying forward decades of relay provision into a smartphone-native format.
How Relay UK Works on a Mobile Phone
On mobile, there are two ways to use Relay UK. The simplest is the dedicated Relay UK app, available free of charge from the Apple App Store and Google Play. Once downloaded and set up with a registered mobile or landline number, the app allows users to type their side of a conversation; the relay assistant reads that text aloud to the hearing person and simultaneously types what is said back. The assistant's typed transcription appears on the user's screen in near-real time, allowing a conversation to proceed at a natural pace.
Where the app is not available or preferred, the older dial-prefix system still works. To call a hearing person, a Relay UK user dials 18001 followed by the full number including the area code. To receive a call, the hearing caller dials 18002 followed by the deaf or speech-impaired person's number; the relay assistant connects in and facilitates the conversation. Both prefixes work from mobile handsets on all UK networks. The app-based route is generally preferred for its richer experience, including the ability to review conversation transcripts, but the prefix system provides a fallback on any phone capable of making voice calls.
Ofcom's Requirement for Operator Support
Ofcom's general conditions, which bind all providers of publicly available telephone services in the UK, include an explicit obligation to ensure access to relay services. General Condition C4 (and equivalent provisions under the successive frameworks) requires that disabled customers are not disadvantaged in their ability to make and receive calls. This means no UK mobile network operator may block or degrade access to the 18001 and 18002 prefixes or prevent the Relay UK app from functioning on their network as a matter of regulatory obligation, not merely commercial goodwill.
Ofcom periodically reviews compliance with accessibility obligations and can take enforcement action against providers who fail to meet them. The Communications (Access for Disabled People) provisions also interact with the Equality Act 2010, which places a duty on service providers to make reasonable adjustments. For mobile users, this reinforces the practical expectation that Relay UK access should function on pay-monthly, pay-as-you-go, and SIM-only plans across all major and virtual network operators.
Accessing Relay UK: The App and the Prefix System
Setting up the Relay UK app involves downloading it, entering the user's own phone number, and optionally adding a list of frequently called numbers. The app works over an internet connection (Wi-Fi or mobile data) for the text component, while the actual voice leg of the call travels over the standard telephone network. This means that in areas with poor data connectivity but reasonable voice signal, users may find that the prefix method is more reliable; conversely, in Wi-Fi environments the app may provide a cleaner experience.
For deafblind users who use braille displays or screen readers, the Relay UK app is compatible with common assistive technologies on both iOS and Android. RNID (formerly Action on Hearing Loss) provides guidance on setup and troubleshooting. There is no registration required to use the 18001/18002 prefix system from any phone; the app requires only a one-time number registration to link an account.
| Access Method | How to Use | Best For | Requirement |
|---|---|---|---|
| Relay UK App (outgoing) | Download app, type your side of the call | Smartphone users who prefer a text interface | iOS or Android device; data or Wi-Fi |
| Relay UK App (incoming) | Hearing caller dials your number normally; app alerts you | Receiving calls without a TTY device | App installed and registered |
| 18001 prefix (outgoing) | Dial 18001 + full number from any phone | Any mobile or landline; no smartphone needed | TTY/minicom or type-capable device |
| 18002 prefix (incoming) | Hearing caller dials 18002 + your number | Deaf user with TTY; hearing callers who know the system | No action required from deaf user beyond answering |
| 999 Emergency via Relay UK | Dial 18000 from any phone or use app emergency feature | Emergency calls for relay-dependent users | UK network access; no pre-registration required |
Costs and How Relay UK Calls Are Billed
The Relay UK service itself is provided without charge to the end user. However, the underlying telephone call — the voice leg that carries the relay assistant's voice to the hearing party — is subject to normal call charges as applied by the user's mobile operator. In practice, most UK mobile plans include unlimited or very generous inclusive call minutes, so the majority of Relay UK calls will consume included allowance rather than incur additional charges. Pay-as-you-go users on tariffs that charge per minute for outgoing calls should be aware that charges apply at their standard rate.
For calls to freephone (0800 and 0808) numbers, the same rules apply as for direct calls: these are free from mobile phones, including when made via Relay UK. Calls to 03 numbers are charged at the same rate as calls to 01 and 02 geographic numbers. Ofcom's numbering rules and the obligation to treat relay-assisted calls the same as direct calls mean operators cannot impose a surcharge specifically for using the relay prefix.
Who Can Use Relay UK
Relay UK is not means-tested or diagnosis-gated. Anyone who finds it useful — whether registered as deaf, hard of hearing, speech-impaired, or simply finding voice calls difficult — may use the service. There is no application, assessment, or qualification process. For those with progressive hearing conditions, early familiarity with the service can be valuable so that it is already set up when communication becomes more challenging.
RNID, Deaf UK, and the British Deaf Association all signpost Relay UK as a core communication tool. The service is also relevant for people supporting a deaf family member: a hearing person can initiate a relay call on behalf of someone who needs assistance navigating the setup process. The relay assistant role is strictly facilitative; they convey messages accurately and do not add to or interpret the conversation, maintaining confidentiality throughout.
What this means in practice
Priya, who is profoundly deaf and lives in Leicester, needs to contact her mobile network's customer service team about an incorrect charge on her bill. She opens the Relay UK app on her Android smartphone, types in the customer service number shown on her bill, and initiates the call. The relay assistant reads her typed message aloud to the call-centre agent: "I have been charged twice for the same data add-on in April." The agent's spoken response — "I can see that on the account, I'll raise a credit now" — is typed back by the relay assistant and appears on Priya's screen within seconds. The entire conversation, including the confirmation of a refund, takes roughly eight minutes. The call uses minutes from her inclusive monthly allowance; no additional charge is applied for using the relay.
Related Guides
How we verified this
This article draws on Ofcom's general conditions of entitlement (specifically General Condition C4 on accessibility), the Communications Act 2003, Ofcom's published guidance on relay services and accessibility obligations, and the official Relay UK service documentation. Information on call charging was cross-referenced against Ofcom's numbering rules for freephone and 03 numbers.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
What is Relay UK?
Relay UK is the national text relay telephone service for the United Kingdom. It allows deaf, deafblind, hard of hearing, and speech-impaired people to make and receive phone calls with hearing people by connecting both parties through a trained relay assistant, who converts text to speech and speech to text in real time. BT operates the service under regulatory obligation.
How do I use Relay UK on a mobile phone?
Download the free Relay UK app from the App Store or Google Play, register your phone number, and type your side of conversations rather than speaking. Alternatively, dial 18001 before any number to make an outgoing relay call from any mobile. Hearing people who want to call you via relay dial 18002 followed by your number. Both methods work on all UK mobile networks.
Is Relay UK free?
The relay service itself carries no charge. The underlying phone call uses standard call minutes from your mobile plan. Most UK contracts include inclusive call minutes, so most Relay UK calls cost nothing extra. Pay-as-you-go customers are charged at their normal per-minute rate for the voice leg. Calls to freephone numbers (0800/0808) remain free from mobile even when made via relay.
Does Relay UK work with all UK mobile networks?
Yes. Ofcom's general conditions require all providers of publicly available telephone services in the UK, including all mobile network operators and virtual network operators, to ensure their customers can access text relay. The 18001 and 18002 prefixes must not be blocked or degraded. The Relay UK app functions over any mobile data or Wi-Fi connection.
Can I use Relay UK to call emergency services?
Yes. Dialling 18000 connects a relay-dependent caller to the emergency services via a trained relay assistant. This works from any phone on any UK network and does not require pre-registration. Deaf users should also consider registering for the 999 SMS service (text 'register' to 999) as an additional emergency access route that does not require a relay assistant.
