gsm-ussd is a script to send USSD (Unstructured Supplementary
Services Data) queries to your broadband provider. USSD queries
are "phone numbers" like "*100#", which will result in a message
(NOT a SMS) with your current prepaid account balance.

You can use this program to query your own phone number,
replenish your prepaid account, query your free minutes left
and so on, depending on your GSM provider.