Bogus phone numbers

Since we are a lead generated company I was following up with some leads I recently pulled.  Some phone numbers are good...but for the ones that aren't, I wish they would just enter a really obvious dummy number...you know like 555-1212 or 111-111-1111..This would save me and probably several other people so much time.  I know how it is, I don't want to give my number out to sales people either.  I guess it is probably asking too much.