These are not good times to be a Telstra shareholder.

Australia's most widely held company, with a million shareholders, has seen its share price tank over the last few years.

Around $40 billion has been wiped off the value of the company since Andy Penn replaced David Thodey as chief executive on the May 1, 2015.

Telstra shares are trading around $2.86, the lowest level since 2011 and not far off the company's record low just above $2.50 in late 2010.

Despite raking in billions from the sale of its copper network to the NBN, Telstra is caught in a highly competitive battle for mobile customers, which is seriously hurting earnings.

And Mr Penn's critics are not impressed.

"It's really no excuse to suggest that after all this time they have not been able to come up with a resolution to be able to stem the bleeding," said fund manager Elio D'Amato from Lincoln Indicators.

An earnings downgrade on Monday sparked another 8 per cent fall in Telstra's shares as they hit a seven-year low.

"The competition is substantially different from the past. We are seeing a resurgent Optus, we are seeing a resurgent Vodafone," explained Foad Fadhagi, CEO of telco research house Telsyte.

"Telstra hasn't got it all its own way as it did in the past."

And it's not just the big players that are eating away at Telstra.

New kids on the block like Kogan and Boost Mobile are part of a stampede into the mobile space.

"There's 180 providers of mobile phone services in Australia, and in 2017, the fat tail of those 180 service providers took 53 per cent of new customers," said Roger Montgomery, founder of Montgomery Investment Management.

Telstra faces a $3 to $4 billion NBN earnings hole

While Telstra's earnings from both mobile and fixed-line services are falling, billions are still coming in from the sale of its network to the NBN.

However, that won't last forever, and the market is wondering how that money will be replaced.

"Telstra's receiving one-off payments for moving people off the copper network onto the NBN, and that will leave about a three or four-billion-dollar hole in Telstra's earnings in the future," Roger Montgomery estimated.

Not this year though, with Telstra indicating it could earn around $2 billion from the NBN.

Lincoln Indicators' Elio D'Amato said it's money that has papered over the problems in Telstra's core businesses.

"Whilst you may have been able to appease shareholders in the near term with a large cash payment, if you have underlying cracks in your operating model, then they will open up in time," he warned.

As a result, Telstra has already cut its prized dividend by more than a fifth to 22 cents a share, and Mr D'Amato thinks more reductions could be on the way.

"We believe there are rising revenue challenges which unfortunately will mean that the company, if it is going to engage in good business practice, will have no choice but to cut the dividend," he said.

Which would raise the ire of Telstra's million shareholders, and questions over how long Mr Penn will last as CEO.

"Taking over from David Thodey has been a difficult task for Andy but it might have been similar for any other leader that's come into that situation," said a sympathetic Foad Fadhagi from Telsyte.

"I don't think he is personally responsible for the market conditions that all the carriers are facing right now."

Telstra's hopes lie in 5G mobile and a 'redundant' NBN

Although Mr Penn didn't create the hole that Telstra finds itself in, Telstra's board will be asking itself if he is the man to get the company out of that hole.

And there is hope on the horizon in the shape of the next generation of mobile technology.

Telsyte's Mr Fadhagi says 5G can't come fast enough for Mr Penn and his team.

A view shared by Montgomery Investment's Roger Montgomery.

"5G will completely replace the NBN," he predicted.

"It will render the NBN redundant and that's where there's money to be made because the NBN revenues will ultimately flow to those who have a 5G network."

But that's the future.

The next profit result is in August and the question is, will Telstra's million strong army of shareholders tolerate another unhappy story.