D-Link DWM-156 User Manual page 5

No (U)SIM card (U)SIM card not inserted or the device
Invalid (U)SIM card The (U)SIM is out of service.
Network signal
Network type
Data service
4. LED Indicator description
State of LED indicator Description
RED Solid On No SIM card/ Error
Green Solid On Register to network (not connect)
Green blinking Connected to network
*Green blinking: Flash once every 0.5 seconds)
Indicate the signal strength of
GSM/GPRS, UMTS.
EDGE available, HSPA