In the United States, the SMS ecosystem has changed significantly with the implementation of the 10DLC — 10-Digit Long Code — standard for A2P, Application-to-Person, traffic.

• Brand and Campaign Registration: It is mandatory to register both the Brand — who is sending — and the Campaign — what is being sent and for what purpose — through an ecosystem called The Campaign Registry.
• Categorisation: The type of messages must be specified, for example: electronic signature notifications, 2FA/OTP or marketing. Each category has different delivery rates and costs.
• Strict Consent — Opt-in: US operators are extremely strict regarding consent. You must be able to prove that the user agreed to receive SMS messages. Messages must always include a clear opt-out option, such as “Reply STOP to unsubscribe”.
• Content Prohibition — SHAFT: It is strictly prohibited to send content related to Sex, Alcohol, Firearms, Tobacco or Cannabis — SHAFT — even in states where consumption is legal. Non-compliance may result in fines of up to $10,000 per message.
• Prohibition of Shorteners: Public URL shorteners, such as bit.ly or tinyurl, often cause campaigns to be immediately blocked by operators such as T-Mobile, AT&T and Verizon.