A new study says the number of mobile operators conducting 5G trials nearly tripled over the past year.

The latest State of 5G Trials report from VIAVI Solutions found that 72 companies are already testing 5G — with 28 of those operators in field trials — and an additional 28 announced plans for 5G trials.

Although the tests were conducted on spectrum ranging from below 3 GHz to as much as 86 GHz, the most common bandwidths were the 28 GHz band followed by the 15 GHz band.

Although carriers generally expect to deploy 5G service in the next year or two, the report also noted that two Middle Eastern providers — Etisalat in the United Arab Emirates and Ooredoo in Qatar — launched pre-commercial 5G services "with limited availability."

Etisalat is also among four operators to report speeds of at least 70 Gbps, along with Kuwaiti company Zain, Belgium's Proximus and Norway's Telenor. Six other carriers reported speeds of at least 35 Gbps, while the remaining 28 carriers to disclose speeds publicly were at 27.5 Gbps or below.

Among U.S. carriers, T-Mobile reported speeds of 12 Gbps and Verizon and AT&T each reported 10 Gbps. Sprint parent SoftBank reported speeds of 19 Gbps.

The VIAVI report also noted that 14 network equipment manufacturers were involved in 5G trials despite global standards that were only approved in December.

"Operators and infrastructure vendors across the globe are moving at varying speeds when it comes to testing and deployment — they need to act now to address technology challenges," IHS Markit analyst Stéphane Téral said in a statement.