I would like some advice

There's this girl who works (pushing trolleys/shopping carts) for the retail store I work at. We've spoken a few times. We seem to have a fair bit in common and get on great. I have her number in my work phone (which I did ask for and she was happy to give it as I need to call her whenever our store needs trolleys). The advice I'd like is, should I contact her outside of work on my personal phone (via text or call) and ask her out for coffee? :)