Phone companies should cap bills for older and vulnerable customers during the coronavirus lockdown, Greater Manchester's mayor has said.
Andy Burnham said companies should find a way to limit charges for over 75s.
He highlighted an offer by BT to introduce a £5 cap on calls for anybody who only has access to landline as a "bare minimum" that should be offered.
Communications regulator Ofcom said call charges were a matter for individual companies.
Mr Burnham was speaking during a phone-in programme on BBC Radio Manchester.
One 80-year-old listener, Mary, said she had been self-isolating since early March and her landline phone was her only contact with the outside world.
She said: "I have no computer, along with thousands of other elderly people. And we're very concerned that at the end of all this our telephone bills, if we do try to communicate with people, are going to be astronomical.
"Is there anything you can do, or the telecommunications industry can do, to help the elderly?"
The government has said anyone struggling to pay their bill as a result of the pandemic would be "treated fairly and appropriately supported".
But Mr Burnham said this support should go further.
He said: "Mary's call really hit home. My parents are in a similar position having not left the house for some time."
The mayor said he recognised the industry was trying to make life easier for the elderly and vulnerable but said the sector needed to introduce a firm cap placed on monthly charges.
He added: "The deeper we get into this crisis the more difficult it will become for people experiencing the effects of isolation, and the more they will need contact with other people.
"BT are the biggest provider of landline services in the UK and they recently announced a £5 cap on the cost of any phone calls made by a customer who only has a landline.
"While others are offering free landline calls it is only for a short window. Therefore I call on the industry to adopt as a minimum the model of BT."
An Ofcom spokesman said it welcomed the "steps phone companies are taking to protect vulnerable customers at this challenging time".
He added: "We advise anyone with concerns about the cost of their landline to contact their provider directly."