Help with AT interface

[nityadevi]

I want to know how the AT command Interpreter indicate NAS when the user dials the number.eg: when the user calls a customer care number, and types the pin , how the AT sends it to NAS.

[symbianyucca]

What is NAS you are refering to ?

And why would you think it is AT commands that are used for dialing and sending DTMF tones (could be, since they do have the commands for both operations)