There are three main SMS sender ID types: alphanumeric (a brand name of up to 11 characters, one-way), numeric long code (a normal phone number, two-way), and short code (a 3 to 8 digit number, two-way, for high volume). Which ones work depends on the destination country and its operators.
The three types compared
| Type | Example | Replies | Typical use |
|---|---|---|---|
| Alphanumeric | MyBank | No | OTP, alerts, branding in most of Europe, Middle East, Asia, Africa |
| Numeric long code | +44 7700 900123 | Yes | Two-way conversations, support, countries where alphanumeric is not allowed |
| Short code | 12345 | Yes | High volume campaigns, keywords, US and Canada marketing |
Alphanumeric sender IDs
An alphanumeric sender ID shows a name instead of a number. The technical limit is 11 characters, using letters, digits and a few symbols such as space, dot or hyphen. It must contain at least one letter, otherwise it is treated as a number. Recipients cannot reply to it.
Alphanumeric IDs are the norm for A2P in most of the world, but rules vary:
- Some countries accept any name without registration.
- Many require sender ID registration in advance, with documents proving you own the brand. Examples include India, Saudi Arabia, the UAE and several others, each covered in its country guide such as India SMS DLT registration.
- Some do not support alphanumeric senders at all. The United States and Canada are the best known examples: A2P traffic there uses 10DLC numbers, toll-free numbers or short codes.
On routes that do not support or do not respect your sender ID, the name may be replaced by a random numeric sender. That is a common sign of an indirect or grey route.
Numeric long codes
A long code is a standard phone number in international format, up to 15 digits under E.164. Its main advantage is two-way messaging: the recipient can reply, and the reply reaches your platform. Long codes come in two flavours:
- Local virtual numbers from the destination country, which recipients trust more and which are often required for two-way traffic.
- International numbers from another country, which some operators block or replace.
In the US, long codes used for A2P must be registered as 10DLC, and toll-free numbers must be verified. See 10DLC and toll-free SMS in the US.
Short codes
Short codes are numbers of 3 to 8 digits (5 or 6 digits in the US and Canada) leased per country and approved by operators for a specific program. They offer the highest throughput and are easy to remember for keyword campaigns ("Text JOIN to 12345"). The cost is higher and approval takes weeks. More in SMS short codes explained.
How to choose a sender ID type
- Check the country rules first. They decide what is possible.
- Decide if you need replies. If yes, use a long code or short code.
- Match the traffic type. OTP and alerts usually work best from a registered alphanumeric name, because users recognise it. See OTP SMS best practices.
- Plan registration time. Some registrations take days, some weeks.
- Test on real handsets to confirm the sender arrives unchanged, as described in how to test an SMS route.
Requesting a route
When you request A2P SMS routes on VoIPMatcher, state the sender ID type and the exact name or number you want to use, so we can source a route that supports it. Request an SMS route with your sender ID.
Frequently asked questions
What is a sender ID in SMS?
The sender ID is what appears as the sender of a text message on the recipient's phone. It can be a brand name such as MyBank, a normal phone number, or a short code such as 12345. Businesses choose it to be recognised, and many countries control which sender IDs may be used for A2P traffic.
What is an example of an alphanumeric sender ID?
Examples are brand or service names such as MyBank, ShopOnline or Acme-Info: up to 11 characters, with letters, digits and a few symbols like a space, dot or hyphen, and at least one letter. Recipients see the name instead of a number but cannot reply to it.
What is the difference between a sender ID and a short code?
A sender ID is any identity shown as the sender, and a short code is one type of it: a 3 to 8 digit number leased in one country that supports replies and high throughput. An alphanumeric sender ID shows a brand name instead but is one-way. Many people use sender ID to mean the alphanumeric name.
What is the character limit for a sender ID?
An alphanumeric sender ID can have up to 11 characters, including letters, digits and a few symbols such as space, dot or hyphen. Some countries add their own limits, for example shorter promotional IDs or required prefixes and suffixes. A numeric sender ID follows phone number rules, up to 15 digits under E.164.
Why is my sender ID replaced by a number?
Either the destination does not support alphanumeric senders, the name is not registered where registration is required, or the route is indirect or grey and cannot carry your name. In the United States and Canada alphanumeric IDs are not used for A2P at all. Check the country rules, register if needed and test the route.
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