What are short codes and long codes?
Both are the "from" number your SMS is sent from — but they behave very differently.
A short code is a special, memorable 5–6 digit number leased through carriers, designed to push large volumes of messages quickly. Think of the numbers brands ask you to text a keyword to.
A long code is a regular 10-digit phone number. It looks like a normal mobile number, supports two-way conversations, and can often handle voice as well as SMS.
Short code vs long code: the differences
Short code | Long code | |
|---|---|---|
Length | 5–6 digits | Standard 10-digit number |
Throughput | Very high (many messages/second) | Lower (often ~1 message/second) |
Direction | Mainly one-way, bulk | Two-way, conversational |
Feel | Clearly a business/brand | Personal, like a real person |
Best for | OTPs, alerts, mass campaigns, keyword opt-ins | Support, reminders, back-and-forth chats |
Setup | Higher cost, longer provisioning | Cheaper, faster to set up |
When to use a short code
- High-volume OTPs and time-sensitive alerts
- Large marketing campaigns and mass notifications
- Keyword opt-in programs ("Text JOIN to 56789")
When to use a long code
- Two-way customer support and reminders
- Lower-volume, personalised conversations
- A local, human feel for regional outreach
Which should you choose?
If speed and scale are the priority — think OTP delivery or a festive-season blast — a short code wins. If you want genuine back-and-forth conversations that feel personal, a long code is the better fit. Many businesses use both, matching the number type to each use case. Helo.ai's SMS product supports the right sender type for your campaign.
Related on Helo.ai: SMS · Sender ID (glossary) · Two-Way Messaging · How to send bulk SMS
Frequently asked questions
What is the difference between a short code and a long code?
A short code is a 5–6 digit number for high-volume, mostly one-way SMS. A long code is a standard 10-digit number for lower-volume, two-way conversations.
Which is better for OTPs, short code or long code?
Short codes are usually better for OTPs and alerts because of their high throughput — they can send far more messages per second.
Can a long code receive replies?
Yes. Long codes support two-way messaging, making them ideal for support and conversational use cases.
Are short codes more expensive than long codes?
Generally yes. Short codes cost more and take longer to provision, but they deliver much higher speed and volume.