What do extended on iphone mean?

I have a iphone through us cellular and the other day I let my sister use my phone and the whole time she said it had extended at the top of screen instead of us cellular so I was wondering was I in a roaming area will I be charge a roaming fee and what if I have a unlimted talk and text plan will I still be charged a roaming fee

If it roamed onto another network you get roaming charges. Once you're roaming whatever deals you get with your usual carrier don't apply.

If you don't want a repeat of the potentially costly consequences then go into settings and turn off call and data roaming, or just turn off data roaming as that's the really costly one.

If your sister made and took no calls whilst roaming, and if none of your social networking/email apps received push notifications and made no postings on your behalf then there won't be any charge for having been connected whilst roaming.