Before you can start sending SMS messages to your voters and supporters, you need to build your SMS contact list. This means that you need to collect their mobile phone numbers and their consent to receive your messages. To do this, you can use your existing contact database and ask people to opt-in to your SMS list. Additionally, you can create a keyword and a short code that people can text to join your SMS list. You can promote this keyword and short code on your online and offline platforms, such as your website, social media, flyers, posters, or billboards. You can also use online forms or landing pages that ask people to enter their mobile phone numbers and agree to receive your SMS messages. These forms or pages can be linked to your online ads, social media posts, or email campaigns. Finally, you can use offline events or activities, such as rallies or voter registration drives, to collect mobile phone numbers from people who attend or participate. You can use paper forms, tablets, or mobile apps to capture their information and consent.