Samsung SCH-S720ZKATFN - Manual (Page 11)

Getting Started 7
Charging the Battery
Your phone comes with a Wall/USB Charger (Charging Head and
USB cable) to charge your phone from any 110/220 VAC outlet.
Note: The battery comes partially charged. You must fully charge the battery
before using your phone for the first time. A fully discharged battery
requires up to 4 hours of charge time.
After the first charge, you can use the phone while charging.
ᮣ Insert the USB cable into the port.
4. Connect the USB cable to the charging head.
5. Plug the charging head into a standard AC power outlet.
6. When charging is complete, unplug the charging head
from the power outlet and remove the USB cable from the
phone.