In recent months I have been getting unsolicited silent calls from, seemingly, various random UK STD numbers on a daily basis. So far today I have had calls from unknown numbers in Glasgow, Birmingham and Luton but the number and STD code varies each time.I think this illegal practice is known as mimicking but I don't understand their purpose as the line is always silent when I answer and cuts off after a few seconds. I haven't tried calling any of the numbers back. They may be genuine numbers that have been hijacked by unknown scammers who constantly choose different numbers from which to call. I assume there is no way to trace the real number these calls are being made from. I haven't tried calling any of them back in case the scammers are trying to get me to do so for phishing purposes or even so they can defraud me by using an extortionate premium rate number for which I will be charged.