How business texts reach UK phones

The text is checked first. CaptiFi Connect works out the encoding and the number of parts, confirms every number is a UK mobile (landlines and other countries are refused with a reason, free of charge), leaves out anyone on your opt-out list and takes the credits. Then the text joins the queue for its route, or waits for its time if you've scheduled it.

From there it's handed to the mobile network, which delivers it to the phone and sends back a delivery report saying whether it got there. Each step is written to the text's timeline: queued, sent, then delivered, or undelivered if the network couldn't reach the phone.

Conversations need a number people can reply to, so one-to-one texts sent from Send SMS or the API without a sender name go out from a real UK mobile number, and so do the replies you send from the inbox. When a customer replies, the reply comes back to that number and into your inbox, threaded with the rest of the conversation. Your answer goes from the same number whenever that number is available.

Campaigns, and anything sent from a sender name, go through a licensed A2P route. A2P stands for application-to-person: texts sent by software to people, which is what business messaging at volume is. Aggregators run these routes, connecting business senders to the mobile networks, and they are how a text can show a name such as your business name in place of a number. A campaign goes out under the approved sender name you pick, or under our default sender if you leave it on Default.

You don't pick a route for each text. It follows from what you're doing, a conversation on a number or a campaign or sender name through A2P, and a credit costs the same on either.

Picture a restaurant using both. Tomorrow's booking reminders go out under the restaurant's sender name, through the A2P route, so guests see the name at a glance. One guest wants to move their table, so the restaurant texts them from Send SMS with no sender name, which sends it from a UK mobile number, and the guest's reply lands in that thread in the inbox. Both come out of the same account and the same credits.

Ofcom's July 2026 rules on scam texts require mobile providers to put volume limits on pay-as-you-go SIM cards, so it's harder to message large numbers of people at once. Business traffic at volume belongs on A2P routes, where the operators and aggregators carrying it have to check who the sender is and keep an eye on what they send.

So CaptiFi Connect splits the work the way it does. A conversation with a customer is person-sized and needs a number they can reply to. A campaign to your whole list is business traffic, and it takes the business route.

Under the rules Ofcom finalised on 15 July 2026, mobile operators and aggregators that carry business messages must run 'Know Your Customer' checks on new senders and 'Know Your Traffic' checks on what they send, such as reviewing account activity and investigating fraud reports. They must check sender names against what they know about the business, and act on reports to block scam texts in transit.

The MEF SenderID Protection Registry sits alongside those rules. Organisations register the sender names they use, so texts that use those names without authority can be blocked, along with a growing list of unauthorised variants.

CaptiFi Connect runs its own checks before any of that. Every new account is checked before it can send (test API keys work in the meantime), and every sender name is checked by our team, including against the MEF registry. It slows the first day down a little, and it means the texts going out alongside yours have been through the same checks.

Delivered means the network reported that the text reached the phone. It doesn't tell you whether anyone read it, because SMS has no read receipts.

Sent means the text has left CaptiFi Connect for the network and the delivery report hasn't come back yet. Undelivered means the network tried and couldn't deliver it, and it's charged because it did go out. Failed means it never left us, and it's refunded automatically.

Reports can arrive late, or more than once. A late or repeated report can't move a text back to an earlier status, and every change is in the text's timeline with the time it happened. If you've set up a webhook, each change is posted to it as message.sent, message.delivered or message.failed.

When someone replies to a text from a real UK mobile number, their network delivers the reply to that number and it comes to us. We match it to the business that texted that person from that number most recently, so a reply to your text lands in your inbox under the sender's number, and we post a message.received webhook if you've set one up. If the reply is STOP or another opt-out word, the number goes on your opt-out list at the same moment.

Replies to a sender name can't happen, because there's no number to reply to. That's the main thing to weigh when you choose between a name and a number.

UK mobiles, including numbers in Guernsey, Jersey and the Isle of Man. Landlines can't receive our texts and other countries aren't covered, so both are refused before sending with a reason, and neither costs anything. A refused number never reaches a network; it shows up in the send's list of rejected numbers instead.