There's no chance that fifth-generation wireless, or 5G, will become available everywhere in two years' time, according to Craig Moffett, who has been a leading telecommunications analyst for years.

Moffett, co-founder of boutique research firm MoffettNathanson, is skeptical that Verizon and other telecom companies can make the transition because spectrum — the range of frequencies an operator network is allowed to radiate — is not sufficient enough in the U.S. to completely support 5G mobile.

"There is a zero chance that 5G is a ubiquitous technology" by 2021, Moffett said Tuesday in a "Squawk Box" interview.

"The standards of 5G were set for insanely wide blocks of spectrum," he said. "You can't find insanely wide blocks of spectrum anywhere but these stratospheric high frequencies."

The 5G standard is meant to be at least 50 times faster than its 4G predecessor. Competition to move to the new technology is fierce.

Verizon turned on its 5G network in Chicago and Minneapolis earlier this month, at an additional cost of $10 for customers with existing unlimited plans. Earlier this month, AT&T said its 5G service went live in parts of seven more cities — Austin, Texas, Los Angeles, Nashville, Tennessee, Orlando, Florida, San Diego, San Francisco and San Jose, California.

Moffett appeared on CNBC shortly after Verizon posted first-quarter earnings that beat Wall Street expectations, however, revenue missed estimates. It raised its 2019 profit forecast.

The MoffettNathanson analyst said Verizon is a "fully valued" stock, but more favorable than AT&T.

So far this year, AT&T stock is up about 12%, but down 8% over the past 12 months. Verizon shares are up nearly 4% in 2019 and almost 20% higher over 12 months.

Correction: Verizon's first-quarter revenue missed expectations. An earlier version misstated its performance.