GoTenna, a Brooklyn-based startup behind a portable personal antenna for smartphones, announced today that it caught a $7.5 million investment. Walden Venture Capital led the series A round, followed by MentorTech Ventures and Verizon subsidiary BBG Ventures.

The investment, the startup says, will be used to grow its team and product pipeline in order to meet the “demand in new markets where central connectivity often fails.”

GoTenna allows users to use their smartphones “even when service is unavailable” by creating their very own radio-wave network. Users can connect to other people who are using GoTenna in areas of low or nonexistent phone reception or Wi-Fi, as long as they are within one mile of each other in cities or four miles in open fields.

The service does not replace cellphone networks, but can be an alternative for when you need to stay connected to a specific person nearby. The company’s site lists “your next ski trip, vacation on a deserted island, music festival excursion, field study in a remote area, or simply keep it on you just in case” as the best uses for the GoTenna.

The antenna, which sells for $199 in a package of two, connects to the smartphone via Bluetooth and lets users “chat 1-to-1, with a group, or even broadcast openly to anyone nearby.”

Bloomberg Beta and also participated in the investment. GoTenna has raised at least $9.3 million since its seed round in 2013.

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