I for one do not give my correct phone number to casinos and do not allow them to call my home. I just do this to avoid my number being used for solicitations.
I assume there are a lot of players who do not wish others in their household to know about their play and would dislike a call for that reason.
Also, many play after hours when spouse and kids are in bed. No calls wanted there either.
And how about those who play at work?
Just give bonuses after a certain amount of play instead of up front.
You will eliminate wagering requirements as well as fraud, and you will improve retention.
No need to get any info but the email address.