AT&T shares are worth leaving in the portfolio, despite the sell recommendation recently issued by one industry analyst, CNBC's Jim Cramer said Monday.

He doubled down on his belief that there is substantial upside in the stock price, thanks to activist investor Elliott Management's position in the teleco giant.

"If AT&T were trading in the $40s or even the mid-$50s, where Elliott believes it can go if the company hits its long-term targets, then the stock would be a sell here," the "Mad Money" host said. "But at $38, AT&T's already trading like those estimates are unlikely. And, hey, if management can deliver, I see this stock going much, much higher."

Cramer was responding to a thesis put forth by MoffettNathanson's Craig Moffett, one of two analysts with sell ratings, according to FactSet. The firm in November downgraded the stock from neutral, assessing a "cloudier" path to meet its 2020 and three-year guidance. AT&T's wireless business would need substantial growth in order to offset weakness elsewhere, Moffett said.

AT&T's revenue is estimated to reach $182.8 billion in 2022, about 7% higher than the $170.8 billion it recorded in 2018, according to FactSet.

"Even if he's right that it's borderline impossible for AT&T to hit its forecasts for 2022, I don't think any of the bulls are really banking on those numbers," Cramer said. "This is a forced turnaround play, meaning Elliott Management is forcing AT&T to get its act together."

Conceding to Elliott Management's demands, AT&T in October agreed to add two new members to its board, pay off debt from the acquisition of Time Warner and sell off as much as $10 billion of its non-core business assets next year.

Admitting that investors should be skeptical about the company's targets, Cramer said the activist firm is "holding AT&T's feet to the fire" after "over a decade of complacency.

AT&T could benefit from the roll out of the fifth-generation of wireless technology, known as 5G, and an iPhone upgrade cycle over the next two years, the host said.

"Put it all together, I think Moffett's missing the forest for the trees with this sell recommendation," Cramer said. "If the company can't make real progress toward its long-term guidance, I have to believe Elliott will come down on them like a ton of bricks and bring in a new team."

AT&T shares dropped more than 4% the day Moffett, who has a $30 price target, made the sell call. The stock has since recovered those losses and is up more than 33% on the year.

The stock closed Monday's session down 0.42% to $38.04.

"If you buy the stock here, you're betting that the company has a lot of room to improve with more focused leadership," Cramer said.