An innovative 'screenphone' promises to bring telephone technology to millions of deaf and hard of hearing people in the UK for the first time.

The phone, produced by manufacturer Geemarc in association with the Royal National Institute for the Deaf (RNID), has a big screen in addition to the normal handset, which displays incoming speech as text.

The text is provided by a Typetalk operator, who listens in and types the words as they are spoken. Typetalk is a free service run by the RNID and BT to provide speech-to-text services.

Dr Mark Downs of the RNID said: "This is an exciting breakthrough for people who are losing their hearing and can no longer use the telephone."

As deafness increases, the ear becomes less able to distinguish one sound from another. That makes it harder to understand a conversation by distinguishing parts of speech, and means that it's not sufficient to amplify the speech in a call.

Ginny Kanka from London, who has profound hearing loss and who tested the phone for the RNID, said: "Screenphone is brilliant and very easy to use. Before, I had to have a hearing member of my family standing next to me to help with voice conversation."

To make a call using the phone, it's neccessary to dial a special number to connect a Typetalk operator to the conversation. The phone has a button to press when a transcription is required. The RNID says the Typetalk service is confidential and operates 24 hours a day, every day.

The phone is available now from the RNID and costs £233.83 including VAT, although some people may be eligible for a refund of the tax paid. The Typetalk service is free and calls are charged at normal rates.