Sender ID vs dedicated number: which should you use?
TL;DR: A sender ID shows your brand name on one-way SMS; a dedicated number lets customers reply and those replies appear in your Inbox. Choose a sender ID when recognition matters more than conversation, and a dedicated number when two-way SMS matters.
Quick decision guide
- Choose a sender ID if you mainly send branded updates, promos, or notices and do not need replies. Recipients see a short business name instead of a number, but they cannot reply.
- Choose a dedicated number if customers need to answer, ask questions, or confirm details. Replies land in your SMSFlow Inbox so you can follow the thread.
- Use both if some sends are one-way brand messages and other work needs conversation. Set a default sender in Account settings and pick the right option when you send.
- Check display and format first. Sender IDs are 2-11 characters, need at least one letter, use standard ASCII, and cannot include spaces. Dedicated numbers are phone numbers people can save and reply to.
- Plan setup and cost. Request a sender ID from Account settings; SMSFlow lodges the ACMA application for you. A free dedicated number comes with any credit purchase; extra numbers are $10 per month each. See pricing for credit packs.
More detail below if you need it.
What each option does in SMSFlow
Sender ID
A sender ID is a short brand label that appears as the "from" name on the handset. You request it under Maintenance, Account, General. The form is largely pre-filled; SMSFlow lodges the application with ACMA on your behalf. ACMA typically approves or rejects within 24 hours.
Format rules in plain terms:
- Length between 2 and 11 characters
- Standard ASCII characters (letters, numbers, and supported symbols)
- At least one character that is not a digit (numbers-only IDs are not allowed)
- No spaces anywhere, and no leading or trailing underscores
- Uppercase and lowercase are treated the same
The hard trade-off: people who receive messages from a sender ID cannot reply. That makes a sender ID a weak fit for support, booking confirmations that expect a yes or no, or any flow that needs a response in the same channel.
Dedicated number
A dedicated number is a number only your business sends from. It helps customers recognise you as a consistent source, and they can reply. Inbound messages show in Inbox with time, linked contact (if they exist), and thread context.
You still answer with the Send SMS feature, not from inside Inbox. That keeps outbound sending in one place while Inbox remains the place to read what came back.
You get a free dedicated number with any purchase of credits. If you need more than one, additional dedicated numbers are $10 per month each. Request numbers from the same Account General area where you manage default sender and business details.
Side-by-side comparison
| Factor | Sender ID | Dedicated number |
|---|---|---|
| How it displays | Brand name (2-11 characters) | Phone number |
| Can recipients reply? | No | Yes |
| Where replies go | Not available | Inbox |
| How you respond | One-way only | Use Send SMS |
| Setup path | Request form; ACMA decision | Request number; free with credit purchase |
| Best fit | One-way branded SMS | Two-way conversation |
When each choice usually wins
Sender ID often fits launch notices, promo blasts, shipping updates that do not need a reply, and any message where the brand name on the lock screen matters more than a back-and-forth.
A dedicated number often fits appointment reminders that invite a reply, service businesses that field quick questions, and any list where you already know customers will write back.
If you are unsure, start with the dedicated number you receive when you buy credits, then add a sender ID once you know which campaigns stay strictly one-way.
Pitfalls to avoid
- Expecting replies on a sender ID. They will not arrive. Move two-way traffic to a dedicated number.
- Submitting a numbers-only sender ID. It must include at least one letter or non-digit character.
- Treating Inbox like a full chat client. You view inbound messages there; you send the answer through Send SMS.
- Skipping account checks. SMSFlow is for Australian businesses. You need a valid ABN, an Australian mobile, email verification, and 2FA. You cannot send until email and ABN verification are complete.
FAQ
Can customers reply to a sender ID?
No. Recipients cannot reply when you send with a sender ID. Use a dedicated number if replies matter.
Do dedicated-number replies show in Inbox?
Yes. Inbound messages from numbers you have messaged before appear in Inbox. Reply with Send SMS, not from inside Inbox.
Is a dedicated number free?
You get a free dedicated number with any purchase of credits. Extra numbers are $10 per month each. Credit options are on the pricing page.
How long does sender ID approval take?
SMSFlow lodges the ACMA application for you. ACMA will approve or reject within about 24 hours.
Can I keep both a sender ID and a dedicated number?
Yes. Request both, set a default sender in Account settings, and choose what fits each message.
Who can use SMSFlow?
Australian businesses with a valid ABN. Sending is limited to verified accounts.
SMSFlow in brief
SMSFlow is an Australian web platform for sending SMS to Australian numbers, managing contacts and groups, using templates and placeholders, viewing Dashboard and sent or unsubscribe reports, and working with an API (keys and webhook URL under Account Developers). Campaigns are available in beta. Billing is credit-based; some messages use more than one credit. New signups receive 50 free credits after you register.
Next step
If branded one-way SMS is enough, request a sender ID after your account is verified. If customers need to reply, take the free dedicated number when you buy credits, then send from the platform or API.
Try SMSFlow free · Contact us if you want help choosing.