In telecommunications, Received Signal Strength Indicator (RSSI) is a measurement of the power present in a received radio signal.
The RSSI of the modem is indicated by a negative dBm value. This value relates to the signal strength of the cellular signal from the tower to the modem. The higher the number, the better the signal. The exact numbers vary between cellular carriers. However, -70 dBm and higher values usually equate to the modem being in an excellent coverage area. The closer to 0 dBm, the stronger the signal. There is a point at which trying to obtain more signal delivers diminishing returns, because the quality of the connection is defined by more values than just RSSI (you will find more information on the other measurements in the Mobile Signal Strength Recommendations page).
|>= -70 dBm||Excellent||Strong signal with maximum data speeds|
|-70 dBm to -85 dBm||Good||Strong signal with good data speeds|
|-86 dBm to -100 dBm||Fair||Fair but useful, fast and reliable data speeds may be attained, but marginal data with drop-outs is possible|
|< -100 dBm||Poor||Performance will drop drastically|
|-110 dBm||No signal||Disconnection|
|> -65 dBm||Excellent||Strong signal with maximum data speeds|
|-65 dBm to -75 dBm||Good||Strong signal with good data speeds|
|-75 dBm to -85 dBm||Fair||Fair but useful, fast and reliable data speeds may be attained, but marginal data with drop-outs is possible|
|-85 dBm to -95 dBm||Poor||Performance will drop drastically|
|<= -95 dBm||No signal||Disconnection|