An SMS short code is a short number, usually 4 to 6 digits, leased in one country and approved by mobile operators for a specific messaging program. Short codes support high throughput and two-way keyword campaigns ("Text JOIN to 12345"), but they cost more and take longer to set up than long numbers or alphanumeric sender IDs.
How short codes work
A short code is valid only in the country where it is issued: the same digits mean nothing on networks abroad. To send from it, the code is provisioned on each mobile operator's network, usually through an aggregator that holds connections to those operators. Recipients can reply, which makes short codes useful for opt-in keywords, polls, support and two-way services.
| Property | Short code | 10DLC or long number | Alphanumeric sender |
|---|---|---|---|
| Length | Usually 4 to 6 digits (5 or 6 in the US and Canada) | Full phone number | Up to 11 characters |
| Replies | Yes | Yes | No |
| Throughput | Highest | Limited, depends on registration | Depends on route |
| Setup time | Weeks | Days to weeks | Hours to weeks, depending on registration |
| Cost | Lease plus setup, highest | Low | Low, sometimes registration fees |
Other sender types are compared in SMS sender ID types.
Dedicated, vanity and shared codes
- Dedicated random code: a code assigned to one brand, digits chosen by the administrator.
- Vanity code: a code with digits you choose, for example one that spells a word on the keypad. It usually costs more.
- Shared code: one code used by many brands, separated by keywords. US carriers no longer allow shared short codes for A2P, and many other markets discourage them, because one bad sender can get the whole code blocked.
Short codes in the US
US short codes are leased through the Common Short Code Administration (CSCA) and then approved by each carrier for a specific program. The application describes the use case, the opt-in flow, sample messages, and how STOP and HELP are handled. Carrier approval commonly takes several weeks, so plan ahead. Once live, short codes give the highest throughput available for US A2P traffic, which is why they are used for large marketing programs and high-volume OTP. The other US options, 10DLC and toll-free, are explained in 10DLC and toll-free SMS in the US.
Short codes elsewhere
Many countries have short codes, but rules differ. In some markets they are mainly used for two-way services and premium-rate SMS, in others they are a normal A2P sender. Length, lease terms and approval process are set by each country or each operator. In countries where alphanumeric sender IDs work well, most one-way A2P traffic uses them instead, because they are cheaper and show the brand name. Check each market before you budget a short code program.
When a short code makes sense
- High peak volumes that would exceed long number limits, such as flash sales or large OTP spikes.
- Keyword-based opt-in campaigns promoted on posters, TV or packaging.
- Two-way programs where an easy-to-remember number matters.
For low-volume or one-way traffic, the cost and setup time are rarely worth it.
Running a short code program well
- Keep content inside the approved program. Changing use case without approval can get the code suspended.
- Handle STOP, HELP and opt-in confirmations exactly as described in the application.
- Monitor delivery and opt-outs per carrier, as in SMS delivery rate and latency.
- Respect restricted categories. See SMS content restrictions.
- Protect keyword and sign-up flows from abuse, as described in SMS pumping.
Costs to budget
A short code program usually includes the lease (paid monthly or quarterly), a setup or provisioning fee with the aggregator, per-message fees, and sometimes carrier fees. Compare the total cost with the alternatives in how A2P SMS pricing works.
VoIPMatcher sources A2P SMS routes from its carriers, including routes for short code traffic where available. Request an SMS route with the country and the program you plan.
Frequently asked questions
What is the difference between a short code and a long code?
A short code is a number of usually 4 to 6 digits, leased in one country for an approved program, with the highest throughput. A long code is a normal full-length phone number, cheaper and quicker to set up but with lower throughput. Both support replies; short codes suit large campaigns, long codes conversations and lower volumes.
How long does it take to get a short code?
In the United States, carrier approval of a short code program commonly takes several weeks after the code is leased through the Common Short Code Administration. Other countries set their own processes, and some take longer. Plan the short code well before the campaign date, with the use case, opt-in flow and sample messages ready.
Can a short code be used in several countries?
No. A short code is valid only in the country where it was issued; the same digits mean nothing on networks abroad, or belong to someone else. An international program needs a separate code in each country, each with its own lease and approval, or a different sender type such as an alphanumeric ID.
How do I find who owns an SMS short code?
In the United States, the Common Short Code Administration offers a directory where you can look up which brand leases a code. In other countries, the operators or the regulator hold this information, and access varies. If you receive unwanted messages from a short code, replying STOP usually ends that program's messages to you.
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