By Elaine Okyere
BBC News, London
Walking to her home in east London after a night out Damaris Cooke saw a motorist hit a cyclist.
The trial of a 999 SMS text service will be launched this autumn
Like any passer-by she knew she had to call for help.
"Someone was walking ahead of me and she attended to the cyclist," said Ms Cooke.
"When I approached I could see clearly that she wanted me to call 999.
"I didn't want to tell her that I was deaf because I felt it would have added more hassle to the situation."
The 25-year-old had to run down two streets before she found someone who could call an ambulance.
Most Londoners take it for granted they can use a phone to call 999 whenever they want, but deaf people can face difficulties.
"I do not like feeling helpless," Ms Cooke said. "If an accident occurred I would feel guilty for not being able to do anything because of my deafness, even though it is not my fault."
There may now be a solution for people like Ms Cooke.
A national trial is being launched this autumn to help deaf people send text messages to contact the police, ambulance, fire rescue and coastguard.
The new system will allow hard of hearing people to send a text to 999 to contact the emergency services.
If the trial is successful the service could be up and running in 2010.
For the estimated nine million deaf and hard of hearing people in the UK the new service will transform the way they call for help in an emergency.
Ruth Akins, from Barkingside in east London, experienced the same feeling of helplessness when a friend fell ill.
"I was dumbstruck and horrified at my inability to help my friend.
"I realised I couldn't call the ambulance because of my deafness. It had never occurred to me before, and perhaps stupidly I never thought I'd be in this situation."
Fortunately another person was able to make the call and Ms Akins' friend made a full recovery.
Currently deaf people can use a textphone to contact the Metropolitan Police, London Ambulance Service and London Fire Brigade via Text Relay.
The service, run by Royal National Institute for the Deaf (RNID) and paid for by BT, enables people with textphones to type a message to an operator who makes the voice call on their behalf.
The downfall of this system is that a hard of hearing person without a textphone nearby would have to find someone to call 999 on their behalf.
BT advises deaf people who use an ordinary phone to call the emergency services to try to make as much noise as possible or tap on the handset, but there is a danger the operator could cut off the call if they do not believe it is genuine.
In some parts of the country, including the South West and Hampshire, a similar text service is in operation.
In these areas the emergency services are already responding to texts sent to 80999.
The messages received are sent directly to the police control room and a controller then calls for assistance from any of the emergency services.
Guido Gybels, director of technology at the RNID, said: "At the moment we have a very fragmented regional service, and, in an emergency, deaf people may not remember the number or even know it.
Guido Gybels believes an emergency text service could help save lives
"Quite clearly access to the emergency services can be a matter of life and death.
"People who find themselves in difficult or tricky situations cannot help - this is a real barrier in 2009."
For the past six years government bodies, telecommunications groups and the RNID have been working to find a way to install a national emergency service text or SMS number.
Mr Gybels believes the new text message system could help save lives.
He said: "We hope to create a solution so that people with hearing impairments are on an equal footing with the rest of society.
"It is not a perfect system, but it is better than having nothing."