In the filing for the unreleased product, Sonos calls it "a high-performance wireless speaker and part of the Sonos sound system. The device's primary function will be for streaming with Wi-Fi, but also features Bluetooth audio streaming and Bluetooth Low Energy, used for simplified setup."
Like Apple and its HomePod, Sonos has used Bluetooth Low Energy in its devices before to make setup easier, but support for Bluetooth streaming would be a new thing in the Sonos lineup and allow users to play audio from any Bluetooth-enable device within range.
The addition of Bluetooth support is particularly surprising given that Sonos has belittled Bluetooth audio listening experiences in the past.
After the FCC filing emerged, The Verge had a chance to see more images of the speaker and has spoken to a person familiar with its capabilities.
According to the source, the speaker is both taller and slightly wider than the Sonos One, and it supports hands-free voice commands from Amazon Alexa and Google Assistant. The portable speaker charges via a base station, and can also optionally be recharged over USB-C.
There's also an integrated handle on the rear and a button that switches between Bluetooth and Wi-Fi. As with other recent Sonos speakers, the portable one will support Apple's AirPlay 2.
Last week, Sonos sent out media invites for meetings later in August, so there's a good chance that the company will use those to unveil the Bluetooth-supporting portable speaker, along with other products due to be launched in the fall.