Of course, they need to track their consumer's buying pattern and plan their marketing strategies. My advice is don't give the real phone number to this third-party. One day, they might use this information for other things that you might don't ever think. You also have the right to not giving your number to any other third-party, so why act so fool to give them.
Today, a lot of scenario have happened when some people making money by selling your personal information.
The real thing that might mostly will happen is, they will send sms to you telling their latest promotion or sales.
