The disclosure comes in the wake of a report that found one million older people suffered from acute loneliness, while two-and-a-half million more were afraid of being alone.
Lesley Carcary, of campaign group Action on Elder Abuse Scotland, said there was evidence some pensioners returned the devices because cold callers were their only source of conversation.
She said: “We know of one elderly person who was targeted first by phone to get her to sign up for work she didn’t need.
“But from there it escalated to the point where the man in question was coming round to her house and the woman was prepared to make him food and do his washing purely as a means of having someone to talk to.
“It is so important that we raise awareness of just how devastating loneliness can be.”
As part of a trial by Trading Standards into the effectiveness of nuisance call-blocking technology, devices were installed into the homes of hundreds of elderly people.
The subsequent findings revealed that the average pensioner was bombarded with 60 cold calls a month and telemarketing companies were deliberately targeting people with dementia as they believed they were more likely to cave in to their demands.
One of the study’s conclusions is that every elderly person could benefit from nuisance call-blockers in their home.
Ms Carcary said: “The issue is not about the effectiveness of call-filtering technology, it’s about ensuring we don’t get to a situation where the most vulnerable feel they’ve nowhere else to turn for social interaction.
“This reinforces the need for loneliness to be treated as a public health priority.”
The grim findings were echoed by community campaigner Richard McShane, who established the Easterhouse Phoenix Project to help pensioners in Glasgow. He said: “You have to reach out to these pensioners as they built these communities so we can’t just kick them to the curb.The more of them that come to the club the better, as we can see what a difference it makes feeling like people care and there is somewhere to go.
“The fear factor kicks in and people are afraid to go out of their homes.”
Age Scotland also said it had also heard of examples of the elderly longing for nuisance calls “just to listen to someone speak”.
A spokesman added: “Around 42,000 older Scots are estimated to feel lonely. This can have a serious effect on their mental and physical health and has been likened to having a 15-a-day smoking habit and is twice as harmful as obesity.”
Loneliness and isolation could be as damaging to health as poor housing and poverty, a report from MSPs revealed last month.
The Equal Opportunities Committee have called on the Scottish Government to prioritise loneliness as part of the public health agenda. In June, the UK Government announced plans to distribute free call-blocking technology to those deemed to be at a high risk of “financial damage and personal distress”.