[Asterisk-Dev] Line status detection for Zap ifaces ( fxo ) ( cont'd )

[Gabriel Rojas]

It seems that's pretty easy to incorporate proper FXO line reporting to
dialplan, at least with regard to BUSY. dsp->f.subclass has such state
when ast_dsp_process() returns to zt_read(). My idea was to generate a
global variable DIAL_FXO from within ast_dsp_process by calling
pbx_builtin_setvar_helper(). But DIAL_FXO doesn't appear to be global when
called that way ( headp and &globals don't match ). Could I just make
headp = &globals and then the variable would be global? My understanding
of asterisk code is still in early stages. Could somebody give a little
explanation of how dialplan variables are handled? TIA