Extensions question

Hello,

I have

exten => s,1,Goto(planusers,${CALLERIDNUM},1);

where calleridnum is the calling party number

The calling person is supposed to be send to the planusers context with the extension of his callerid. If there is not extension programmed the user should here a message and asterisk should hangup.
How can asterisk check if the extension exist before sending the call to it?
i want to be able to do this:

if calleridnum exists in plan users go there if not go somewhere else

Also, I dont want to use the context invalid ext because i use it for something else.

thx

Maybe include => planusers in your original context and just do a goto CALLERID(num) and have a wildcard match anything else.

Can you show me an example with the wild card.

I got it

exten => _.! ,1, goto (…

it worked thx