Is it possible to background SayDigits() like Background() can?
You could background the digit recording. They are in /var/lib/asterisk/sounds/digits IE:
Background(digits/20)
so how do you background the equivalent of
exten => _X.,n,SayDigits(${EXTEN:1}) ?
or
exten => s,n,SayDigits(${CALLERID(number)})) ?
Not sure. But you could make Festival generate a recording from the variable and then background that file.