The Government have already made it mandatory for marketing firms to display their calling line identification (CLI). Ofcom have also adopted a new CLI rule relating to communications providers, which will enable the telephone number of the person making the call to be displayed to the receiver. The new rules become effective in October 2018.
Ofcom have also formed a Strategic Working Group consisting of nine major communications providers, with the aim of exploring technical measures to block and stop unlawful nuisance calls. As of the end of 2017, six of nine working group members were routinely blocking problematic calls at the network level, and/or offering their customers a free service to block or divert problematic calls. More information about this can be found in the report at https://www.ofcom.org.uk/__data/assets/pdf_file/0023/110957/nuisance-calls-joint-action-plan-2018.pdf.