You can place a TMR definition on a skin to execute a command on a timed interval (or you can use RRExtender's global timer feature).
However, there's no way to check the contents of a custom label right now (because we assume that the application setting the label already knows the content), which means that would have been added.
In any case, if you can find a COMMAND that Freefone executes when the phone is connected, you can try to execute something using exectbl.
for instance, if freefone executes this command to set the label when it first comes on:
you can try adding to exectbl:
However, you may need to use variables and so on to prevent your command from executing several times and so on.