[asterisk-users] DAHDI works, but returns CHANUNAVAIL ??

[sean darcy]

  DAHDI 2.6.0, dahdi show status
Description                              Alarms  IRQ    bpviol CRC 
Fra Codi Options  LBO
Wildcard TDM400P REV I Board 5           OK      0      0      0 
CAS Unk           0 db (CSU)/0-133 feet (DSX-1)

Dahdi 1 is an internal extension, dahdi 4 is pstn.

This call completes. But DAHDI comes back with CHANUNAVAIL. This a 
problem since we then test for CHANUNAVAIL to use an alternative provider.

    -- Executing [s at DialOut:17] Dial("DAHDI/1-1", "DAHDI/4/1XXXYYYZZZZ") 
in new stack
     -- Called DAHDI/4/1XXXYYYZZZZ
     -- Hanging up on 'DAHDI/4-1'
     -- Hungup 'DAHDI/4-1'
   == Everyone is busy/congested at this time (1:0/0/1)
     -- Executing [s at DialOut:18] NoOp("DAHDI/1-1", ""Dialstatus is 
"CHANUNAVAIL"") in new stack

Any ideas?

sean