A national action plan to crack down on the growing problem of "nuisance" phone calls has been criticised by organisations representing the elderly as "too little, too late".
The communications regulator Ofcom launched the initiative as it published figures showing that almost half of all UK adults have received such calls – double the proportion seen a year ago.
Charities representing older people said they were more likely to be affected than other groups, as they are more often at home during the day and tend to be more dependant on landlines.
The regulator promised new research to create a clearer picture of the problems consumers experience, and a sample of UK adults will keep a diary recording any calls they receive, holding on the line long enough to be able to determine the nature of the call and detailing their experience.
It will work closely with industry to set out ways to trace companies behind nuisance calls where they try to hide their identity, and to look at ways to prevent such calls. It also aims to improve compliance, writing with the Information Commissioner's Office to businesses making calls in the UK warning them to abide by Ofcom's rules on silent and abandoned calls.
Silent calls are usually caused by automated dialling systems used in call centres, and Ofcom's research makes it clear their use is rising sharply.
In February 2011, the maximum fine for regularly making such calls was raised to £2m. Ofcom issued fines totalling more than £800,000 within the past year to HomeServe and npower, while TalkTalk is being investigated.
During a six-month period in 2012 almost half (47%) of all adults with a landline experienced a silent call, up from a quarter (24%) in 2011.
Over the same period, almost three quarters (71%) of landline customers said they received a live marketing call, while 63% received a recorded marketing message.
Ros Altmann, director general of Saga, said only stiffer penalties would help deter companies persisting in nuisance calls: "The only thing that is new about this is the research – and the new figures are very worrying.
"We are concerned about the disproportionate impact on older and vulnerable people. The landline is the lifeline for many older people and they are also more likely to be made anxious as a result of the calls. The Telephone Preference Service is supposed to help, but BT says it has only a 85% success rate."
Michelle Mitchell, director general at charity AgeUK, said: "A hike in silent calls is very disappointing news, particularly for older people since they cause a great deal of anxiety and distress.
"Older people should be on their guard and speak to a trusted relative or friend before handing over money or giving personal information to someone they don't know."
A spokesman for Ofcom said: "We understand the anxiety that nuisance calls can cause, particularly for older consumers. This is a complex and challenging area, but Ofcom is determined to work with industry and other regulators to help protect consumers."
