Hi Lily Lee, this is an unfortunate but common important lesson most entrepreneurs have to learn, get a contract and have the task well defined. When things aren't clear and payment is required in advance: use deposits or escrow.
These things are there to protect both sides and minimize risk.
As for phone numbers there are valid reasons to have a non local number, i use several services to lower international costs and to not have to give out my personal number. Be direct and ask them for thier local number this is a much better litmus test than connection quality.