U.K. cellular carrier Vodafone will launch its 5G network in 2019, the company confirmed, but concerns over the size of early 5G devices are casting a cloud over the next-generation wireless technology’s initial mass market potential. That’s the message from Vodafone CTO Scott Perry (via Telecoms), who held court after the company made the U.K.’s first live holographic call over 5G at a media event.

Vodafone’s plan calls for a three-stage rollout of 5G services in the U.K., beginning with the October 2018 launch of 5G tests in seven cities, continuing with full launches in London, Manchester, Liverpool, Birmingham, Cornwall, and the Lake District in 2019, then expanding to 1,000 5G sites by 2020. Rather than focusing solely on urban areas, Vodafone said it’s “launching in rural areas where there is great data growth based on innovation,” amusingly tagging a cow’s black spot with a Vodafone logo to highlight its interest in agricultural IoT applications.

But based on visits to unnamed companies in the United States, Perry believes that early 5G devices won’t be small enough for scalable mass-market launches until the end of 2019 or 2020. He indicated that battery and antenna challenges were pushing early devices to 2 or 3 times current devices’ sizes, an issue that could certainly limit their pocketability and ergonomics.

It’s worth noting that Qualcomm recently pushed back against suggestions that devices using its 5G modems will be oversized, noting that its prototype phones are made to be large for anti-drop protection and easy reconfiguration during carrier tests. The…