Have you tried phoning that number and asking them. Not to do so smells of dishonesty. If you do not have the full telephone number usually the few digits after the code will give the area within that city.
ive tried googling numbers in the past. this would me more effective with 0845 type numbers though. otherwise do 141 to withold your number and ring it. if its a company they are likely to say the company name. if its an individual you may recognise the voice. once the person has answered just say "wrong number" and hang up.