Sony Ericsson W600i / W550i

I just got this phone and so far it's great. I'm coming from an LG 6000 so there are a few things to get used to. But one thing I'm wondering is how do I display phone numbers with a dash in them ie. "555-555-5555"

Right now, every number is being displayed as "5555555555." I can't seem to find a setting anywhere in the menus?

Thanks.