The glasses have a USB 2.0 high speed On-The-Go (OTG) port (the mag connector), which can be either a device port (when connecting the glasses to a PC or laptop), or a host port (needed for connecting to other devices, like a USB to WiFi dongle, or USB hub).
Glasses as USB Device:
The first cable comes with the glasses; The standard mag to USB std A cable that ships with them configures the glasses as a USB device. When plugged into a host, if it is not fully charged and is running an App that is busy, the device can draw up to 2.4A @5V. If one were to connect the glasses to a phone or tablet acting as the USB host, this would probably not work since most phones or tablets can not source this much current. Even most laptops can't source this much power, although laptops usually handle it gracefully by communicating with the device about it's power needs and then limiting the current to the device as needed, the result being that the glasses may not charge as quickly. Phones/Tablets appear to not handle this well. Most phones are designed to be devices too, and do not handle sourcing power as a host. Better to use the Power Hub, making the glasses the Host, and the Phone or Tablet the device.
As a device, you can communicate with a laptop/PC using adb. The R-6 can also enable USB tethering in this configuration, where it acts as a DHCP server and assigns an IP address to the Laptop/PC. (R-7 does not yet have this feature. If this is something you'd be interested in, let us know and we can evaluate raising it's priority on the feature roadmap).
Glasses as USB Host:
The second type is an option - the cable we supply that enables the port as a host is for connecting to our external battery pack (The Power Hub), which has a single USB Standard A receptacle (female) port, just like any PC or laptop. You'd need that accessory for attaching up to USB device peripherals (cameras, adapters, hub, keyboard, mouse, etc.).
There are two other ways you could connect a phone to the glasses. One would be to make your phone a WiFi hotspot/access point, and connect to it from the glasses as the WiFi client; this is the supported configuration we use all the time. We know IP routing works, and there are no wires needed.
The other approach would be to use our external battery pack, which when connected to the glasses via a mag to mag cable, makes the glasses a USB host, and provides a device port to plug your phone into. In this configuration, the battery pack charges the glasses AND the phone, and provides 10x battery capacity. This is a supported configuration today for the R-6, but is not yet supported for the R-7. If this is something you'd be interested in, let us know and we can evaluate raising it's priority on the feature roadmap.