you can call telephone preference service and they will stop junk calls getting through and if any do get through you can report them to them and they get stopped.
we have it at home and rearely get calls these days, which is great
you have to call your provider and they send you a form to fill in.
What is TPS?

The UK's Telephone Preference Service (TPS) is a central opt out register whereby individuals and consumers can register their wish not to receive unsolicited sales and marketing telephone calls. It is a legal requirement that companies do not make such calls to numbers registered on the TPS.

The original legislation was introduced in May 1999. It has subsequently been updated and now the relevant legislation is the Privacy and Electronic (EC Directive) Regulations 2003.

Registration is free of charge and is open to UK consumers at their residential address, sole traders and, except in Scotland, partnerships. Once a number has been registered it will become effective in 28 days.

The Telephone Preference Service is not government funded and is paid for by the direct marketing industry