A VBUS conductor is checked to determine whether a voltage on the VBUS conductor is greater than a vSafe0V voltage within a detect time interval. A device policy manager applies a vSafeDB voltage to the VBUS conductor when the voltage on the VBUS conductor is greater than the vSafe0V voltage. The policy engine waits for a bit stream to be detected within a timer interval. When the bit stream is not detected within the timer interval, the device policy manager is instructed to apply the vSafe0V voltage to the VBUS conductor. The device policy manager applies a vSafe5V voltage to the VBUS conductor when the bit stream is detected, and the policy engine waits for the bit stream to stop within a device ready timer interval. When the bit stream has stopped within the device ready timer interval, the policy engine sends capabilities as a source port.