"Catch all" extension

Hi all,

What do you think about having a single extension in the dialplan that matches everything and then delegates the next action to an external application through AGI? I mean something like this:

exten => _.,1,AGI,catchall.agi,${EXTEN}

Then, catchall.agi could EXEC dialplan macros in function of choices (e.g. SQL queries to perform LCR, …)

I think it could be powerful… but what could I miss here?