AT command set

They usually are used from a PC, where the phone is visible as a modem (via a real or virtual serial port) to command the phone to do something. Connection requirements depend on the phone model (what it supports); main thing is for the phone to be visible as a modem, as already mentioned.

For Nokia models the AT commands supported are described on documents like these:

http://www.forum.nokia.com/info/sw.nokia.com/id/95672052-6c77-488d-a055-acef77e4cdc5/AT_Command_Set_For_Nokia_GSM_And_WCDMA_Products_v1_2_en.pdf.html

http://www.forum.nokia.com/info/sw.nokia.com/id/aed70945-0ca1-4cc9-beaf-89273f16bcd5/AT-help.pdf.html

http://www.forum.nokia.com/info/sw.nokia.com/id/537978cf-3542-41ea-a220-9a0bbbb83580/AT_Command_Set_For_Nokia_CDMA_Products_v1_1_en.pdf.html

garg_shal wrote: I am using Nokia 3100 then How can i use these command.