Republic Wireless, a U.S. mobile operator that was a pioneer in Wi-Fi-first mobile service, is adding a GSM network to its prior reliance on the Sprint network. That concept–relying on Wi-Fi access and then defaulting to the mobile network when necessary, is an approach Illiad Free in France earlier had adopted, and likely will be adopted by cable TV operators entering the mobile business as well.

Republic Wireless also is adding a number of high-end smartphones to its lineup of handsets, which, up to this point has been very limited.

The new Android phones include the Moto X Pure Edition, Google Nexus 6P by Huawei, Google Nexus 5X by LG, Samsung Galaxy J3 (2016), Samsung Galaxy S6, Samsung Galaxy S7 and Samsung Galaxy S7 Edge.

For potential new customers who prefer to use such handsets, the device expansion will make Republic Wireless a more-attractive option

Also, like Google Fi, Republic Wireless customers using the new handsets will have access to both the Sprint and the GSM network for mobile fallback.

The company’s “Bonded Calling” feature senses suboptimal conditions on the Wi-Fi network and can respond by patching the gaps in a Wi-Fi call with redundancy on the mobile data network.

These patches result in a higher quality conversation and extend the range of indoor coverage. Bonded Calling is another step forward for Republic’s “Adaptive Coverage” technology platform.

“When it comes to Wi-Fi calling, engineering innovation is one of our hallmarks, and what makes Republic different from other carriers is that we are continually pioneering unique new improvements,” said David Morken, Republic Wireless CEO. 

“We’ve long said two networks are better than one – Wi-Fi is a terrific network in optimal conditions as is cellular, but intelligently pair the two networks together and you have the best of both worlds,” said Morken. 

“Until recently, we engineered for optimal voice quality on Wi-Fi in an ‘either – or’ scenario – either calls traveled over the WiFi network assuming sufficient quality conditions or calls were automatically and seamlessly handed over to the cellular network,” he said. “And any calls made on cellular network stayed on the cellular network.”

“Last year we were the first provider to announce seamless Cell to Wi-Fi handover – that is the ability to hand calls made on the traditional, circuit-switched cellular network back to WiFi,” said Morken.