If you can't make phonecalls, or find it very difficult to make them, you can register your mobile phone number with the Emergency Services by texting Register to 999. They will then send you a text message reply, which you respond Yes to. Once you do that, your number is registered with them, and you will be able to alert them by text message if you need one of the emergency services. For example, you may need to send a message such as:
'ambulance. man having a heart attack. outside post office. valley road, Watford'
They say 999 calls are the best way of contacting them, but for those people who can't speak on a phone, this is a brilliant service. 