Around 100 jobs will be impacted by the closure of telesales at energy giant SSE.
The company said it intends to redeploy 70 employees in Thatcham, Berkshire, and around 30 back office staff members in St Mellons, Cardiff, to other jobs in the company "wherever possible".
SSE - one of Britain's ''big six'' energy suppliers - said it is ending the practice of cold calling potential customers, but will still call current customers and people who have agreed to be contacted.
The company's energy supply brands - Southern Electric, Scottish Hydro and SWALEC - will only contact customers they already have a relationship with or potential customers who have previously agreed to a call, SSE said.
A small team will be established to deal with inbound calls from potential customers but they will not make unsolicited outbound calls, the company said.
SSE intends to redeploy the employees whose jobs are impacted "within customer service or other areas of the company wherever possible".
In April, SSE customers were urged to seek compensation from the company after Ofgem announced it was to be fined a record £10.5 million for ''prolonged and extensive'' mis-selling.
Energy watchdog Ofgem said it found ''failures at every stage of the sales process'' across SSE's telephone, in-store and doorstep selling activities, adding that the level of the fine reflected the seriousness and the duration of the mis-selling, as well as the harm caused to customers and the likely gain to the company.
SSE provided ''misleading and unsubstantiated statements'' to potential customers about prices and savings that could be made by switching to SSE, according to Ofgem.
Management at SSE failed to pay enough attention to compliance, which allowed the mis-selling to take place, added Ofgem.
Will Morris, SSE's group managing director, retail, said the decision to end cold calling shows the company is "dedicated to delivering what customers want".
He said: "Nobody likes receiving a sales call out of the blue and so we are stopping it.
"It doesn't matter that other energy companies still do it, or other industries for that matter, cold calling is not something that a company like SSE - committed to providing an excellent customer experience - should be doing any longer.
"We want to be a company that sells itself, one that is recognised for being the best in its sector and one that people choose to buy from.
"This decision to end unsolicited calls is part of becoming that company and demonstrates that we are dedicated to delivering what customers want."
Research carried out by Which? found that eight out of 10 people asked had received an unsolicited call in the last month, and 8% had received 50 or more, SSE said.
A quarter of the people asked said they felt intimidated by cold calls.
A spokeswoman from watchdog Consumer Futures said: "This is good news from SSE - the impact of nuisance calls on consumers can range from inconvenience to genuine stress.
"It is a victory for common sense as it does not make good business sense to badger potential customers. We now need to see other suppliers follow suit."
Which? executive director Richard Lloyd said: "Our research shows the energy industry is one of the main culprits for cold calling, so it's good to see a big supplier commit to ending unsolicited sales calls, and we hope other energy companies will now also stop this nuisance."
A spokeswoman for SSE said the company made three million cold calls per year prior to today's announcement.