Investors tend to "sit up and take notice" when a stock rallies 12% on good earnings, TheStreet's Jim Cramer, co-manager of the Action Alerts PLUS portfolio, said on CNBC's "Mad Dash" segment.

Cramer meant Dycom Industries (DY) - Get Report , a specialty telecommunications contracting company, which topped earnings per share and revenue expectations by a wide margin.

The company's good results bode well for a more familiar name: AT&T (T) - Get Report . "AT&T is doing very well," Cramer said, "maybe better than we think." Otherwise, Dycom wouldn't have had such a great quarter because AT&T is its largest customer.

"AT&T made a good deal when it bought DirecTV," he added. Dycom will continue to benefit from the expansion of AT&T's broadband business, as well as fiber networks like that of Alphabet's (GOOGL) - Get Report Google Fiber.

Cramer said he likes AT&T, Verizon (VZ) - Get Report and T-Mobile (TMUS) - Get Report  but does not like Sprint (S) - Get Report .

Image placeholder title

At the time of publication, Cramer's Action Alerts PLUS had a position in GOOGL.