I need the user to select the suburb that they live in. It's no good just entering any old text, it has to match one of the suburbs in my database.

My current implementation is an auto-complete text box in a form, where the user must select one of the auto-complete options. This strikes me as a bit confusing - it is not obvious that you can't just enter your own text and submit the form, but must select one of the autocomplete options.

Obviously the database list of suburbs is quite large, and there is not much space on a mobile device to display autocomplete options.

What is the best way to do this?