Possibly. Do the trial with a new number on one email account. Then if you like the plan here port in but use a different email address because if you use the 15 day trial account I don't think you would be considered a new customer. If somehow Visible detects fraud you will be likely end up paying full price. This is provided you have a phone that shows it is compatible to even get a SIM.
I think you would be better off just signing up for the offer and if you don't like it you can just leave after the first month. One thing to point out is if you need help from customer service there is no one to talk to by phone, it is done by chat which is usually up to an hour wait maybe more and an hour plus to fix issues if they can even be fixed. They can also be contacted via Facebook messenger and Twitter but it the same unknowing agents. If you value customer service you might be better off. Just scroll through a few pages in this section of the forum and it will give you an idea of what you would be in for. I put up with it because of the cost of the plans otherwise I wouldn't even own a cellphone yet. I have read out porting out issues also. Read up on those also.
Good luck with your decision.