I'm having an intermittent issue where asterisk will play our greeting to the caller, and then drop the call instead of making our phones ring.

I'm unable to reproduce the problem with any phones I have here, and many callers get through just fine. Some callers though, run into the problem, and I can't find any pattern to it.

The bit of information I could find said it was caused by an error in evaluating a dialplan expression. I'm thinking it's this line:

exten => START,n,GotoIf($[${FORCE_CLOSED}=TRUE]?CLOSED,1)

But I'm not sure what's wrong with it.

I see the following error on the console:

[Apr  4 16:29:49] WARNING[27038]: ast_expr2.fl:459 ast_yyerror: ast_yyerror():  syntax error: syntax error, unexpected '=', expecting $end; Input:=TRUE^

Surrounding Console output:

-- Executing [START@AGInbound:1] Answer("IAX2/AtlantaTeliax-10086", "") in new stack
-- Executing [START@AGInbound:2] BackGround("IAX2/AtlantaTeliax-10086", 0000_AG_THANK_YOU_FOR_CALLING_AG") in new stack
--  Playing '0000_AG_THANK_YOU_FOR_CALLING_AG.slin' (language 'en')
[Apr  4 16:29:49] WARNING[27038]: ast_expr2.fl:459 ast_yyerror: ast_yyerror():  syntax error: syntax error, unexpected '=', expecting $end; Input:
=TRUE
^
[Apr  4 16:29:49] WARNING[27038]: ast_expr2.fl:463 ast_yyerror: If you have questions, please refer to doc/tex/channelvariables.tex in the asterisk source.
    -- Executing [START@AGInbound:3] GotoIf("IAX2/AtlantaTeliax-10086", "?CLOSED,1") in new stack
    -- Executing [START@AGInbound:4] GotoIfTime("IAX2/AtlantaTeliax-10086", "9:30-17:0|mon-fri|*|*?OPEN,1") in new stack
    -- Executing [START@AGInbound:5] GotoIfTime("IAX2/AtlantaTeliax-10086", "10:0-18:30|sat|*|*?OPEN,1") in new stack
    -- Executing [START@AGInbound:6] GotoIfTime("IAX2/AtlantaTeliax-10086", "12:0-17:0|sun|*|*?OPEN,1") in new stack

Relevant lines from the dial plan:

exten => START,1,Answer()
exten => START,n,Background(0000_AG_THANK_YOU_FOR_CALLING_AG)

; See if we're open
; Force Closed if no one's going to be answering
exten => START,n,GotoIf($[${FORCE_CLOSED}=TRUE]?CLOSED,1)

exten => START,n,GotoIfTime(${AG_WEEKDAY_OPEN_HOUR}:${AG_WEEKDAY_OPEN_MIN}-${AG$
exten => START,n,GotoIfTime(${AG_SATURDAY_OPEN_HOUR}:${AG_SATURDAY_OPEN_MIN}-${$
exten => START,n,GotoIfTime(${AG_SUNDAY_OPEN_HOUR}:${AG_SUNDAY_OPEN_MIN}-${AG_S$
; ...and we're not. But maybe the time of day has been overridden?
exten => START,n,GotoIf($[${OVERRIDE_TIME_OF_DAY}=TRUE]?OPEN,1)
; No override... We're definatly closed.
exten => START,n,Goto(CLOSED,1)

Any idea what's wrong with the expression? We recently upgraded from 1.4 to 1.6.