On the Cisco IP Phone 7970, it is not possible to access the Audio Preferences under Settings since the audio settings are disabled to prevent the selection of external devices when IP phones are used with inline power supply.
The Cisco IP Phone 7970G can operate with two types of power supplies, In-Line Power and Full-Power mode. With its backlit color display and touch screen, the Cisco IP Phone 7970 requires more power than other Cisco IP Phones. The default power supply solutions do not provide sufficient power in order for the Cisco IP Phone 7970 to operate in full-power mode.
In order to use certain features, for example, in order to adjust the brightness of the LCD window or to use an external microphone or external speakers on the Cisco IP Phone 7970, it is required to use a Cisco approved external power supply.