Sender ID is the identifier displayed to recipients showing who sent the SMS message. In the US, this is typically a phone number (10DLC, short code, or toll-free).
Sender ID Types
Numeric (US standard):
10DLC: 10-digit local number
Short code: 5-6 digit number
Toll-free: 1-8XX number
Alphanumeric (Limited in US):
Brand name as sender
Up to 11 characters
One-way only (no replies)
Not supported by US carriers
US Sender ID Requirements
In the United States:
Must use registered phone numbers
No alphanumeric IDs for marketing
Must be capable of receiving replies
Must be registered for 10DLC
Sender ID Best Practices
1. Use consistent sender ID
2. Register all numbers properly
3. Match sender to content type
4. Consider local area codes for trust
5. Avoid switching numbers frequently
Why Sender ID Matters
Trust: Recipients recognize your number
Deliverability: Registered IDs get better delivery
Replies: Enables two-way conversation
Compliance: Required for 10DLC registration