Please help with catch-all SIP Incoming Route

I have to setup a general purpose SIP Incoming Route.

It should simply route the incoming calls the same way
for the sip://9007@foo.com call, route to extension 9007
for the sip://9006@foo.com call, route to extension 9006
and so on …

Don’t care about the trunk and Caller ID Number.
They will be blank.

For the Set Destination, what should I enter for Custom App?

Please help.
I don’t have much experience with routing and I’ll get myself into trouble.
Thanks.