Sender ID
US recipients see your number, so put the brand in the message text. Alphanumeric IDs are an international feature with their own registration rules.
What shows up at the top of the message thread is route-dependent. In the US, A2P messages display the sending number — your 10DLC long code, toll-free number, or short code. Brand identity is conveyed inside the message ("Acme Co: your order shipped") and, increasingly, through RCS verified sender branding.
Many other markets (UK, much of Europe, Asia-Pacific) support alphanumeric sender IDs — up to 11 characters like ACMECO — often with country-specific pre-registration requirements. Alphanumeric senders are one-way: recipients cannot reply, which conflicts with US STOP-reply requirements and is part of why US carriers never adopted them.
Compliance intersection: CTIA expects the brand name in message content since the number alone does not identify the sender, and consistent sender numbers matter — rotating numbers to dodge filtering (snowshoeing) is itself a violation pattern carriers hunt.
Frequently asked questions
Related glossary terms
10DLC (10-Digit Long Code) is the US carrier-mandated framework for sending Application-to-Person SMS from local 10-digit numbers, requiring brand and campaign registration with The Campaign Registry.
A short code is a 5- or 6-digit phone number leased for high-volume A2P SMS, offering the highest throughput available but costing roughly $500-$1,250 per month plus a multi-week approval process.
RCS (Rich Communication Services) is the carrier-grade successor to SMS, supporting verified branded senders, rich cards, suggested replies, and read receipts. RCS Business Messaging requires agent verification, and TCPA consent rules apply as they do to SMS.