Zte CDMA2000 1X EV-DO User Manual page 38

Select ring tone
After clicking "Ring", you could set different ring tones for Call coming, New message,
Call connected, Call disconnected and Waiting call.
After the setting, click "Apply" button to save the settings on the current interface.
Click "Default" button and then "Apply" button to restore the settings on the current
interface to factory default.
Supplementary Services
After clicking "Service", you could set "Unconditional forwarding", "Busy Forwarding",
"No answer forwarding", "Call waiting", etc. Double-click the selected option to modify
the service number and forwarding number.
ZTE Corporation
CDMA2000 1X EV-DO Wireless Data Terminal User Guide
http://www.zte.com.cn