A top executive at Verizon Communications has encouraged investors to think of 5G as an “overlay” to the existing 4G LTE network and not a complete overhaul.

Speaking at the MoffettNathanson Media and Communications Summit 2016, Verizon CFO Fran Shammo said LTE will still be the dominant network technology for the future and that 5G will supplement 4G. He also said that, at least initially, 5G will be a fixed service – used as a broadband replacement technology – and not a mobile service.

Shammo’s comments are notable, because many 5G equipment vendors have been pushing 5G use cases that involve connecting cars and all types of devices, many of which will be mobile.

While Shammo acknowledged that some use cases will involve mobility, such as smart city applications, he said the majority will be fixed. “Now, not a ton of stuff needs to be mobile on 5G; it’s mainly fixed,” he said. “And that’s where our trials are.”

Verizon has said it will have a fixed wireless 5G pilot available in 2017. Many believe the company’s emphasis on fixed wireless may be because it plans to use it as a way to expand its FiOS video and broadband service beyond its existing wireline footprint.

Verizon 5G Technology Forum partners – which include vendors like Nokia, Ericsson, Intel, Qualcomm, and Samsung – have filed paperwork with the FCC to get special temporary authority to test equipment in the 28 GHz band. Those companies also revealed in a video blog from Verizon that replacing wired connections for wireless is one of the key use cases they are working on.

Interestingly, Shammo also said he doesn’t believe software-defined networking (SDN), which is considered a building block for 5G, will result in lower capex for the company, because 5G will require a very dense network. In other words, to make 5G possible, Verizon will have to deploy more small cell sites (often called microsites) and more fiber to backhaul the traffic on the 5G network, which is costly.

Last month Adam Koeppe, vice president of technology planning at Verizon, told attendees of the Brooklyn 5G Summit that Verizon is pushing ahead with virtualization so that it can more quickly deliver changes in services to customers. “Change is expected to be in real-time so customers can get the benefits the fastest," Koeppe said. 

Verizon also said last February at the Mobile World Congress in Barcelona that it was coordinating with Asian operators KT, NTT DoCoMo, and SK Telecom on 5G through a newly formed 5G Open Trial Specification Alliance. The goal of the Alliance is to share 5G trial information among the operators. A further goal is to help speed along standards development and achieve economies of scale when it comes time to get 5G equipment and devices.

Shammo cautioned that, while some manufacturers will have 5G gear available as early as 2017, it’s unclear at this point whether operators will be deploying 5G in the 28 GHz spectrum or the 39 GHz spectrum. And until there are some standards set around spectrum, it’s uncertain when 5G will be commercially available.