C.29. ISNULL()

ISNULL(value)
Returns 1 if value is NULL (kein Wert), otherwise returns 0.
exten => 123,1,Set(foo=${ISNULL(${Var1})})

Note

Internal help for this application in Asterisk 1.4:
  -= Info about function 'ISNULL' =- 

[Syntax]
ISNULL(<data>)

[Synopsis]
NULL Test: Returns 1 if NULL or 0 otherwise

[Description]
Not available
diff output to internal help in Asterisk 1.2:
- none -