SMS Short Code

An SMS short code is a 5 or 6-digit phone number used specifically for business-to-consumer text messaging at high volume. Instead of sending from a standard 10-digit phone number, businesses using short codes send from numbers like 12345 or 556677. Short codes are designed for high-volume sending — they can handle millions of messages per day — and are pre-approved by mobile carriers for commercial messaging, which improves deliverability.

Shared vs. Dedicated Short Codes

A dedicated short code is exclusively used by one business — only your messages come from that number. A shared short code is used by multiple businesses simultaneously, distinguished by keywords (one business uses the keyword JOIN, another uses OFFER). Dedicated short codes are preferable for established brands: they build recognition (customers learn to associate your messages with your number), carry no risk of another business’s sending behavior affecting your reputation, and allow you to use any keyword you want. Shared short codes are lower cost but have significant limitations and were phased out by major carriers in 2021.

Short Codes vs. 10DLC

Ten-Digit Long Code (10DLC) numbers are standard 10-digit phone numbers that have been registered and approved for business messaging. They are significantly less expensive than short codes and look more like a personal number, which can increase trust and reply rates for conversational campaigns. Short codes, however, have higher throughput (better for mass sends to large lists) and broader carrier support. Most businesses today use 10DLC for conversational SMS and reserve short codes for very high-volume promotional campaigns.

Setting Up a Short Code

In the United States, short codes are leased from the Common Short Code Administration (CSCA) and must be approved by all major carriers before use. The approval process typically takes 8–12 weeks and requires submitting a description of your use case, sample messages, and opt-in/opt-out flows for carrier review. Most reputable SMS marketing platforms manage this process on behalf of their customers.