Use the free sms present in your phone operator subscription to publicize your activity or send updates to your customers.
It’s proved that an sms sent has a opening rate a lot superior compared to the email.
So if you have a shop and you would like to have a promotion, why not use the phone number of your customers to inform them?
Be careful to have their permission to contact them though!
Attenzione ad avere la loro autorizzazione a contattarli pero!