To send SMS online, businesses can choose between using an SMS app or building a custom solution with an SMS API. Once the platform is chosen, a verified phone number must be obtained, which can be local, national, mobile, toll-free, or short code, each with its own advantages and regulations to follow. Verification of the number improves deliverability and compliance with regulatory requirements, such as A2P 10DLC in the US, which requires registration for businesses sending more than 3,000 daily texts. With a verified phone number and an SMS service provider, businesses can start sending text messages online, taking advantage of their high open rate, cost-effectiveness, and permission-based nature to engage customers effectively.