Ericsson R310s - Preparing Your Phone for Use; Front

Trouble Shooting Guide, Standard
4/00021-2/FEA 209 544/31 B 3(23)
V380B: DC voltage for the radio part.
VRTC: DC voltage for the Real Time Clock.
VVCO: DC voltage for the synthesizer.
I2C: Communications standard for two-way communication using only 2 wires,
clock and data.