Sender ID
SMS sender ID for UK businesses
A sender ID puts your business name where the phone number would normally be, so people know who's texting before they open it. You request it in the dashboard and our team checks it before it can be used.
What is an SMS sender ID?
A sender ID is the name a text appears to come from, such as your business name, shown in place of a phone number. In CaptiFi Connect sender IDs are 3 to 11 characters with at least one letter. Our team checks each request, including against the MEF SenderID Protection Registry, and people can't reply to a text sent from one.
How sender names work in CaptiFi Connect
Request a name on the Sender names page in the dashboard, or with POST /api/v1/sender-ids, with a line on what you'll use it for. Our team looks at every request before approving it. We check the name doesn't imitate another brand or a public body, and we run it against the MEF SenderID Protection Registry, the industry list that helps stop banks, government bodies and other registered brands being impersonated by text.
Once it's approved, choose it as the sender in Send SMS or on a campaign, or pass it as sender in the API. Texts from a sender name always go through our licensed A2P route, the route built for business senders.
The registry works by letting organisations register the names they send from, so texts that use a registered name, or a lookalike of it, without authority can be blocked. We check against it before approving a name so that nobody on CaptiFi Connect ends up sending under a name that belongs to someone else.
If we can't approve a name, we'll say why, and you can ask for a different one.
Choosing a good sender name
These help a name get approved, and help customers recognise it:
- 3 to 11 characters: letters, digits, spaces and . & _ -, with at least one letter.
- Use the name customers already know you by, the one on your sign or your website, shortened if it has to be.
- Steer clear of generic names like 'Info' or 'Alerts'. Ofcom's rules ask mobile operators and aggregators to have a policy on generic sender IDs such as 'customer service', and a generic name tells the reader nothing anyway.
- Don't pick anything that could be read as a bank, a delivery firm or a public body. We won't approve it.
Rules and limits that apply
Nobody can reply to a text sent from a name. That's fine for reminders and delivery updates, but it changes how opt-outs work: 'Reply STOP' can't work on a text people can't reply to, so marketing sent under a name needs another simple way out, and anyone who asks should go straight onto your opt-out list.
If you want replies, send from a number. Conversations in CaptiFi Connect go out from a real UK mobile number and replies come back to your inbox.
Ofcom's rules for business messaging, finalised on 15 July 2026, ask mobile operators and aggregators to check each sender ID against what they know about the business behind it. It's also why we ask what a name is for when you request it.
For developers
GET /api/v1/sender-ids lists your names and where each request stands. POST /api/v1/sender-ids requests a new one, with value for the name and an optional purpose.
Once a name is approved, pass it as sender on POST /api/v1/messages or when you create a campaign. A name that has not been approved for your account is refused with the error code sender_not_approved, so nothing goes out under it by mistake.
Get a sender name approved
- 1
Request it
Enter the name on the Sender names page and say briefly what you'll send from it.
- 2
We check it
Our team looks at the name, including against the MEF SenderID Protection Registry.
- 3
Use it
Pick it as the sender in Send SMS or on a campaign, or pass it as sender in the API.
Sender name or UK mobile number?
| Compared on | Sender name | UK mobile number |
|---|---|---|
| Shows as | Your business name | A UK mobile number |
| Can people reply? | No | Yes, into your inbox |
| Opt out by replying STOP | Not possible, so give another way | Yes, handled for you |
| Needs approval | Yes, our team checks each name | No, beyond the check on your account |
| Best for | One-way messages: reminders, updates and campaigns | Conversations, and anything you want answers to |
Questions people ask
Can people reply to a sender ID?
No. A text from a name has no number to reply to. If you need replies, send from a number; conversations in CaptiFi Connect use a real UK mobile number.
How many characters can a sender ID have?
Between 3 and 11: letters, digits, spaces and . & _ -, including at least one letter.
Why was my sender name refused?
Usually because it could be mistaken for another organisation, such as a bank, a public body or another registered brand, or it matches a name on the MEF SenderID Protection Registry. A name outside the format (3 to 11 characters with at least one letter) is refused too. We'll tell you the reason, and you can request a different name.
What is the MEF SenderID Protection Registry?
A registry run by the Mobile Ecosystem Forum where organisations register the sender IDs they use, so texts that imitate them can be blocked.
Can I have more than one sender name?
Yes. Request each one separately and each is checked on its own. Pick whichever approved name fits when you send.
Can I use a sender ID for marketing?
Yes, but give people a way to opt out that doesn't depend on replying, because they can't reply to a name. Change the opt-out line on that campaign so it points somewhere that works.
Send your first text this week
Set up your account and contacts now; we check every new account before it can send.