AT&T shares saw their biggest one-day drop in more than 20 years on Thursday after the telecommunication giant reported earnings. The stock looks like a Buy at current levels, according to analysts at J.P. Morgan.

Although the telecom company's first-quarter results were largely in line with expectations—earnings per share were slightly ahead, with revenue below—shares in AT&T (ticker: T) plunged more than 10% on Thursday, the stock's biggest daily downward move since 2000 . At a closing price of $17.65, the shares are beaten up, even including a 1% rebound in Friday's premarket trading.

"We would be buying here," analysts at J.P. Morgan led by Philip Cusick wrote in a Thursday note. They reiterated an Overweight rating on the stock while trimming their target for the price to $22 from $23.

"We see a very favorable risk/reward," the analysts said, adding they "expect a gradual rebound in shares from this level but no catalyst for it to break above $20 this quarter."

J.P. Morgan's view is that AT&T's fundamentals are solid, but that management could have taken steps that might have forestalled the plunge in the stock.

Alongside a slowdown in subscriber growth for its postpaid phone plans, a nasty spot in the company's earnings was a shortfall on free cash flow, which was in the spotlight after AT&T cut its dividend last year . Free cash flow came in at $1 billion, well short of the $3.2 billion analysts expected.

"AT&T had flagged at conferences that free cash flow would be the low for the year, but clearly could have managed expectations," the analysts said.

"We would like to see management and investor relations more aggressively manage numbers in public events, particularly a number that has so clearly been of intense focus of investors for years," wrote the analysts. "We think management's credibility should improve over time, but until then this share volatility makes investors wary of defending shares in what should have been a very small disappointment."

AT&T didn't immediately respond to a request for comment.

Another argument for buying the stock after the post-earnings tumble is that the selloff may have been exacerbated by market dynamics beyond fundamentals.

"There was some fast $$ in the stock looking for a net adds beat, which contributed to the sell-off," the analysts said. "Over the last six quarters AT&T's average earnings-day volatility of plus or minus 7% belies the increasingly steady results in the business."