According to sources, it belongs to the Child Support Agency (CSA) or DWP offices. You can try to contact CSA Helpline on 0845 713 3133 to check.
If you received an abandoned or silent call from that number you can also contact Ofcom (the communications regulator) on 0300 123 3333 (Monday to Friday from 9:00am to 5:00pm) or 020 7981 3040 to complain.
Just recently, Citizens Advice said that companies should stop cold-calling potential customers after a survey found that 92% of people do not trust sales representatives who cold-call, describing the findings as “indicative of marketing that is nothing more than a nuisance”. Find out more at Mirror.
According to Evening Standard, Culture Minister Ed Vaizey said that there will be stricter laws this year to make it easier for regulators to punish marketing firms responsible for nuisance calls. Find out more here.