# About sender IDs

A sender ID is the name a text message appears to come from: your organisation's name instead of a phone number. People see straight away who the message is from, which makes them more likely to read it and less likely to mistake it for a scam.

## Sender ID or reply number?

| | Sender ID | Reply number |
|---|---|---|
| Shows as | Your name, e.g. `YOURORG` | A phone number |
| People can reply | No | Yes, and replies come back to your account |
| Registration in Ireland | Must be registered with ComReg | Not needed |
| Best for | Notices, alerts and reminders that don't need an answer | Confirmations, surveys and conversations |
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You can use both on the same account and choose for each message.

## Choosing a sender ID

- **3 to 11 characters**, capital letters A to Z only. No spaces, digits or symbols.
- It should clearly identify your organisation. Generic names such as `SMS`, `DOCTOR` or `DENTIST` can no longer be registered in Ireland, and messages with misleading sender information aren't delivered (see section 17.6 of the [terms](/terms/)).
- Your sender ID must match exactly, letter for letter, wherever you register it.

## Getting a sender ID approved

Every sender ID is approved by us before it can be used. Its status is **Pending** until then, and **Approved** or **Rejected** after. Approval usually takes up to 48 hours.

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**In the Republic of Ireland** there's an extra step first: the sender ID must be registered with ComReg, with DiaryBook (the company behind Iflow) assigned as your third party. Follow [Register with ComReg](/docs/sender-ids/register-with-comreg/), then let us know once ComReg has approved it.

**In the UK and most other countries**, there's no national registration step. A few countries' networks don't accept sender IDs at all. If you send there, the message fails with status **9132** and you need a reply number instead.

## What to watch for

**Irish recipients see "Likely Scam"**
The sender ID isn't registered with ComReg, or DiaryBook isn't assigned as the third party on the registration.

**Messages fail with 9104 or 9105**
9104 means the sender ID used isn't valid. 9105 means the account has no approved sender IDs. See [Status and error codes](/docs/reference/sms-status-codes/).

**People reply and nothing arrives**
Messages from a sender ID can't be replied to. Send from a reply number when you need answers.

## Related

- [Register with ComReg](/docs/sender-ids/register-with-comreg/)
- [Replies](/docs/replies-and-reports/replies/)
- [Status and error codes](/docs/reference/sms-status-codes/)

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Source: https://iflow.net/docs/sender-ids/about-sender-ids/