020 3906 1462

They only ring once sop you never pick up the call. This is usually a tactic used by criminals / scammers that are checking old phone number databases to find which numbers are live from the target list. Old number data bases are cheap to buy so petty (amateur) criminals are more likely to be behind this. The number is "not" a genuine number but is actually a VOIP (Voice Over the Internet Protocol) generated number which criminals buy in bulk. The numbers appear to be local but the caller could be anywhere in the world so it is hard to trace these types of numbers. Additionally, block any number that ranges between 02039061460 and 02039061469 as the criminals have to buy blocks of 10 numbers which always begin with the digit 0 through to the digit 9 and this is one of a block. If your phone allows it, don't just block the number but also report it. The more people that report it the sooner the network providers block those numbers.