SMS sender ID requirements: format checklist before you request

TL;DR: Australian SMS sender IDs must be 2–11 characters, use standard ASCII, include at least one non-digit, and contain no spaces or underscores. Check your brand name against this list before you lodge a request in SMSFlow.

Quick format checklist

Use this list to pick a valid sender ID string. If any item fails, change the name before you request it.

1. Length is 2 to 11 characters. Shorter than 2 or longer than 11 won't pass. Count every character, including letters, numbers, and allowed symbols.
2. Use standard ASCII only. Stick to everyday letters, numbers, and supported symbols in the standard ASCII range (decimal codes 32–126). Avoid special fonts, emoji, or non-standard characters.
3. Include at least one non-digit. A numbers-only string isn't allowed. 12345 fails; Shop123 or ACME can work if other rules pass.
4. No spaces and no underscores. Don't put spaces anywhere, including at the start or end. Underscores aren't allowed either. Prefer a compact brand form such as AcmeBooks over Acme Books or Acme_Books.
5. Case doesn't create a new ID. Uppercase and lowercase are treated the same. MyBrand and mybrand are the same identity for matching purposes, so choose the display casing you prefer and keep naming consistent in your team docs.

Once the string passes all five points, you can request it from Account settings in SMSFlow. SMSFlow lodges the application with ACMA on your behalf; ACMA typically approves or rejects within 24 hours.

Try SMSFlow free · More detail below if you need it.

Why these rules matter

A sender ID is the short name that appears instead of a mobile number when your SMS arrives. In Australia, registration sits with the ACMA SMS Sender ID Register. Format rules exist so the ID is readable on handsets, distinct from pure phone numbers, and consistent across networks.

Getting the format right first saves a rejected application and a second trip through the form. It also forces a clear brand choice: the name recipients will see on one-way messages such as promos, launch notes, and service updates.

Important trade-off: people who receive messages from a sender ID can't reply. If you need two-way chat, use a dedicated number instead so replies can land in Inbox. You still send follow-ups through Send SMS, not from Inbox itself.

Good examples vs common fails

More likely to fit the format rules

• AcmeCo (letters, within length)
• ShopAU (letters, clear brand)
• BookBay1 (letters plus a digit, not digits-only)
• VITA-Care only if every character is allowed ASCII and length stays within 11 (hyphens may be acceptable as supported symbols; still avoid spaces and underscores)

Common fails

• A (too short)
• MyLongBrandName (over 11 characters)
• 0412345678 or 123456 (digits only)
• Acme Shop (space)
• Acme_Shop (underscore)
• Leading or trailing spaces typed by accident when copying from a document

Treat the checklist as product-supported format guidance. ACMA can still approve or reject an application on policy grounds even when the string is technically well formed. For primary register information, see ACMA’s SMS sender ID register.

How this fits SMSFlow

SMSFlow is a web platform for Australian businesses that need to send SMS to Australian numbers. You request a sender ID from Maintenance → Account → General (Account settings). The form is largely pre-filled with your business details. SMSFlow lodges the request; you don't run a separate technical integration for the register step.

Before you can send, accounts still go through normal verification: email verification, a valid ABN, Australian mobile details, and 2FA as part of signup. New signups receive 50 free credits. Billing is credit-based; some messages use more than one credit depending on length and content. See pricing for how credits work.

Sender IDs suit one-way branded traffic. Dedicated numbers suit branding plus replies. Pick the channel that matches the conversation you need, not only the display name you want.

FAQ

What are the core SMS sender ID requirements for format?

Length 2–11 characters, standard ASCII, at least one non-digit character, no spaces anywhere, and no underscores. Case is treated the same for matching.

Can my sender ID be numbers only?

No. The ID must contain at least one letter or other non-digit character so it is not confused with a phone number.

Are spaces or underscores allowed in a sender ID?

No. Remove spaces and underscores. Use a compact brand string without padding at either end.

Does capitalisation change my sender ID?

No. Uppercase and lowercase letters are treated the same. Choose a readable casing for display and keep internal naming consistent.

Can customers reply to a sender ID message?

No. Recipients can't reply when you send with a sender ID. Use a dedicated number if you need replies in Inbox and continue the conversation via Send SMS.

Who approves the sender ID after I request it in SMSFlow?

SMSFlow lodges the application for you. ACMA approves or rejects, typically within 24 hours. A valid format doesn't guarantee approval if the name fails register policy checks.

Request a clean sender ID with SMSFlow

SMSFlow helps Australian businesses send SMS from the web platform or API, manage contacts and groups, review sent and unsubscribe reports, and request a sender ID or dedicated number from Account settings. Start with a format-clean brand name, complete verification, and send when your account is ready.

Try SMSFlow free with 50 credits on signup, or contact us if you are unsure whether a sender ID or a dedicated number fits your use case.

Choose a name that passes the five format checks, request it once, and keep one-way branded SMS clear for your customers.