Alphanumeric sender ID: definition and how it works
Published and updated
An alphanumeric sender ID replaces the sending phone number with a short text string such as a brand name, up to eleven characters, on routes and in countries that support it.
How it works
When a recipient sees a message from a name instead of a number, the sender used an alphanumeric sender ID. The SMS standard allows the originating address to be an alphanumeric string of up to eleven characters, and carrier routes in many countries pass it through. It is the most branded sender type and the cheapest, because no number is rented.
It has one hard limit: a name is not an address, so nothing can be sent back to it. Replies fail or vanish. Any use case that needs a reply, including STOP handling in markets that require it, needs a number as well.
Support and rules vary by country more than any other messaging feature. In the United States alphanumeric senders are not delivered on domestic routes. In India a header must be registered on the DLT ledger before an operator will carry it. In several other markets an ID must be pre-registered with each operator, and unregistered IDs are rewritten to a number or dropped. In much of Europe dynamic alphanumeric senders still work without registration, though operators are tightening that over time to fight brand impersonation.
The impersonation problem is why regulators keep restricting the feature: a string that says a bank's name is trivial to set on an unregulated route. Registration ties the name to a verified sender.
How this applies with textbee
textbee cannot set an alphanumeric sender ID because the phone sends from its SIM, and a SIM has a number. The upside is that every message is replyable and there is nothing to register. If a branded name matters more than replies, that is a carrier-route feature.
Related terms
- Sender ID: The sender ID is what the recipient sees in the from field of a text message: a phone number, a short code, or a registered brand name.
- DLT registration: DLT registration is the Indian requirement that any business sending commercial or transactional SMS register itself, its sender headers and its message templates on a distributed ledger run by the telecom operators, under TRAI rules.
- Long code: A long code is a standard full-length phone number, such as a ten-digit United States number, used as the sender of SMS.
- Two-way SMS: Two-way SMS is messaging where recipients can reply to the number that texted them and the sender's software receives and acts on those replies.