Unstructured Supplementary Service Data (USSD)

Although less well known than SMS, Unstructured Supplementary Service Data (USSD) is a method of communicating between the unit containing the SIM card, and data servers hosted at the Eseye Data centres. USSD makes use of the GSM control channels and can be very cost effective for the delivery of small amounts of data moderately frequently.

USSD is particularly useful in low power devices since a USSD message can be sent as soon as the modem has registered on a mobile network. This can save between 30 and 40 seconds of modem-on time, and the corresponding power that would be needed during that period.

USSD messaging is used by many mobile operators to send custom interactive menus to the phone handset.