How can I send DTMF tones generated by the software to a remote location.

To send DTMF Tones this command is used AT#VTS=x,x,x<cr>

Command: #VTS
Function: Generate Tone Signals (Online Voice Command)
Values: The tone generation consists of elements in a list with each element separated by commas.
Default: (see individual parameter descriptions)
Result Codes: OK - command to play tones on currently selected device is accepted; ERROR - command was not issued during Online Voice Command mode or string is grammatically incorrect.
Description: The #VTS action command can be issued to play one or more DTMF or other tones (such as a "beep") if and only if the modem is in the Online Voice Command mode and the sampling rate (see the #VSR command) is set to 7.2 kHz. The modem parses and plays the tones defined in the parameter in the order listed, and no key abort is accepted. The parameter can have three types of elements separated by commas, and following the "#VTS=".

Dual or Single Tones with Variable Duration:

These are represented by the substring [x,y,z] (enclosed in square brackets, "[ ]", as shown) in the parameter field. Each such substring consists of three sub-elements corresponding to the two frequencies (i.e., x and y), and the duration (i.e., z).

[x,y,z] -

x represents the first frequency (0 or 200-3000 Hz)
y represents the second frequency (0 or 200-3000 Hz)
z represents the duration (which is ASCII decimal in units of 100 ms)

DTMF Digits with Variable Duration:

This is represented by a substring {x,z} (enclosed in curly braces "{ }", as shown) in the parameter field. Each substring consists of two sub-elements corresponding to the two frequencies (i.e., x) and the duration (i.e., z).

{x,z} -
x represents the DTMF digit (0-9, A-D,*,#)
z represents the duration (which is ASCII decimal in units of 100 ms)

DTMF Digits with Duration Defined by #VBT:

This is represented by a value x (non-bracketed) corresponding to a DTMF digit (i.e., x) in the parameter field. xx represents the DTMF digit (0-9, A-D,*,#), with the duration defined by #VBT (beep tone timer).

Command options are: #VTS=[x,y,z], {x,z}, and/or x, as described above