Sender ID validator.
Check an alphanumeric or numeric SMS sender ID against the GSM standard: the 11-character limit, the GSM 7-bit character set, and the format rules that decide whether a network will accept, strip or reject it. Nothing leaves your device.
- Length 8 / 11 charactersWithin the 11-character GSM alphanumeric sender-ID limit.
- All characters are in the GSM 7-bit alphabetEvery character belongs to the GSM 03.38 default alphabet.
- Includes at least one letterTreated as an alphanumeric sender ID.
The short answer
What makes a sender ID valid?
An alphanumeric sender ID may be up to 11 characters and every character must belong to the GSM 7-bit default alphabet (GSM 03.38). In practice the safest set is A–Z, a–z, 0–9 and a single space — punctuation is technically in GSM-7 but is stripped or rejected on many routes. A numeric sender follows ITU-T E.164 (up to 15 digits), but long numeric senders are frequently overwritten by networks unless registered as a short or long code. Meeting these format rules is necessary but not sufficient: many countries also require pre-registration of the sender ID before it will be delivered.
The format rules this tool checks
| Rule | Alphanumeric | Numeric |
|---|---|---|
| Maximum length | 11 characters | 15 digits (E.164) |
| Character set | GSM 7-bit (safest: A–Z 0–9 space) | Digits, optional leading + |
| Display | Shown as text on the handset | Shown as a number |
| Reply-able | No (one-way) | Possible for long/short codes |
| Common risk | Rejected if unregistered | Overwritten by the network |
Registration varies by country
Passing the format checks above does not guarantee delivery. A growing number of markets require enterprise sender IDs to be pre-registered with the operator or regulator before A2P traffic using that ID will be delivered; some markets ban alphanumeric senders entirely and mandate short or long codes; others silently replace unregistered senders. Because these rules change and differ by market, this tool deliberately does not assert per-country outcomes — treat it as a format check, and confirm registration requirements for each destination.
Frequently asked questions
How long can an alphanumeric sender ID be?
The GSM standard caps an alphanumeric sender ID at 11 characters. Anything longer is truncated or rejected by the network. Each character must also belong to the GSM 7-bit default alphabet defined in GSM 03.38.
Which characters are allowed in a sender ID?
Technically any character in the GSM 7-bit alphabet, but in practice the only universally safe characters are A–Z, a–z, 0–9 and a single space. Punctuation is accepted on some routes and stripped on others, so this tool flags it as risky rather than valid.
Can I use a numeric sender ID?
Yes, but with caveats. A numeric sender follows ITU-T E.164 (up to 15 digits). Long arbitrary numeric senders are often overwritten or randomised by networks for A2P traffic; reliable numeric sending usually requires a registered short code or long number.
Does a valid format mean my messages will be delivered?
No. Format validity is necessary but not sufficient. Many countries require the sender ID to be pre-registered with the operator or regulator, some ban alphanumeric senders outright, and others replace unregistered IDs. Always confirm the registration requirements for each destination market.
Why does my sender ID appear as a random number on the handset?
Some networks override alphanumeric or unregistered senders — replacing them with a shared numeric gateway number — particularly where the sender ID has not been registered. Registering the ID in the affected market is the fix.
Registering sender IDs at scale?
BroadNet handles sender-ID registration and delivery across 200+ countries and 1,000+ operator connections. Talk to our team about your markets.