If you aren’t happy with the other suggestions made so far, I have one more.
You can build a custom outbound route in extensions_custom.conf, context [from-internal-custom]. There you set up match patterns like you would in an outbound route and manipulate the caller ID like this:
exten => _555NXXNXXX,1,Set(CALLERID(num)=973${CALLERID(num)})
then send the call to the outbound routes and skip the callerid macro (step 1)
exten => _555NXXNXXX,n,Goto(outbound-allroutes,${EXTEN},2)
not tested… good luck!