Nuisance phone calls 'offer home improvements'
Nuisance phone calls are increasingly related to offers of home improvement work, although PPI remains the most common subject, the regulator has said.
The proportion of unsolicited calls that are about payment protection insurance dropped from 22% last year to 13% in 2014, Ofcom found.
But the proportion of calls about loft insulation and solar panels rose.
The regulator added that some nuisance callers were hiding their identity by using "number spoofing".
This tactic means that the number which displays on the recipient's phone is either a false number, or uses the number - without consent - of a legitimate business.
|Nuisance calls - Ofcom research 2014|
|Subject||Proportion of calls|
|Home and loft insulation||8%|
|Home improvements - e.g. kitchens and windows||7%|
|Phone and broadband||5%|
|Financial services and products||5%|
|Accident claims and compensation||4%|
Claudio Pollack, of Ofcom, said a new system of tracing calls was being put into place across the industry but "we are under no illusions that there is still more work to do".
In the majority of cases, unsolicited calls are considered to be annoying by recipients as they may interrupt a meal or work.
The research suggests that PPI calls are starting to be replaced with calls about other "offers" as claims for compensation for the mis-sold loan insurance start to tail off.
This year, 8% of nuisance calls related to loft insulation compared with 2% in 2013. The proportion of calls about solar panels rose from 2% to 6%, and other home improvements accounted for 7% of calls, up from 3%.
Ernest Doku, telecoms spokesman at price comparison website Uswitch.com, said: "Unwanted calls are a modern day scourge that is clearly showing no sign of abating.
"The problem goes beyond our home landlines of course. Nuisance calls and texts plague our mobiles too."
Richard Lloyd, executive director of consumer group Which?, said: "It is encouraging that the volume of unwanted PPI calls is falling, but millions of us are still being plagued by nuisance calls and texts.
"We urge everyone to report calls so that regulators can identify companies who break the rules, and we then need tough enforcement action to tackle this everyday menace."
The regulator has published new guides about dealing with nuisance calls.