Many phone handsets now let you see the number of the person calling before you answer. This feature – known as "Caller ID" or "Calling Line Identity" (CLI) – is a handy way of screening the calls you want to answer from the ones you don't.
Malicious, abusive or threatening calls, whether from people you know or from strangers, are a criminal offence. If you receive such a call you should immediately call your phone company and ask for their nuisance or malicious calls team.
The phone rings, you rush to answer but there's no-one on the line. Abandoned and silent calls can be annoying and irritating at the best of times. But for some people – for example, those living alone – these calls can be particularly frightening.