Google voice and GPT (get paid to) sites go hand and hand. You are probably wondering why I say this.
Lets say you are filling out an offer or a survey but you don't want to give them your personal phone number. You can't give them a fake number because that is just wrong and the advertisers will figure out that you gave them a fake number.
So the next best thing is get a gmail account if you don't already have one. Then sign up for a free Google voice number. It will ask you what number you want your messages to get forward too. Put a personal number in the box. Once you have the Google voice number go into the settings and make sure there is a check next to have phone calls and / or messages go to your email. If you have this check then your personal phone will not ring when you do offers.
Make sure you write down your Google voice number because you don't want to forget what the number is. You can use this phone number on anything you fill out but don't want to get a phone call about.