# Sender ID validator.

- Canonical URL: https://www.broadnet.me/tools/sender-id-validator
- Language: en
- Last updated: 2026-10-21
- Publisher: BroadNet (https://www.broadnet.me)
- Markdown version of the page above, generated from the rendered page.

GSM 03.38 · runs in your browser

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.

8 characters · limit 11 for alphanumeric

Try an example

Looks valid Detected as alphanumeric

- Length 8 / 11 characters Within the 11-character GSM alphanumeric sender-ID limit.
- All characters are in the GSM 7-bit alphabet Every character belongs to the GSM 03.38 default alphabet.
- Includes at least one letter Treated 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.

[Sender ID Registry How operators register and protect enterprise sender IDs.](https://www.broadnet.me/operators/sender-id-registry) [GSM-7 / Unicode Checker See exactly which characters fall outside GSM-7.](https://www.broadnet.me/tools/gsm7-unicode-checker) [SMS Segment Calculator Encoding, segments and cost for the message body.](https://www.broadnet.me/tools/sms-segment-calculator)

## 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.

[Sender ID Registry](https://www.broadnet.me/operators/sender-id-registry) [Contact sales](https://www.broadnet.me/contact)