A UK SMS gateway without the enterprise contract
Reach any UK mobile from a real UK number. Two-way messaging, delivery receipts and inbound webhooks, connected over plain HTTP — no SMPP account, no minimum spend, no sales call.
curl -X POST https://api.useline.io/v1/messages \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"from": "+447700900456",
"to": "+447700900123",
"body": "Your delivery arrives between 2pm and 4pm."
}'Delivery receipts, inbound webhooks & UK numbers included
Try it freeFrom £4/mo · SMS from 3p · No contracts
Writing the integration? See the full SMS API reference
What is an SMS gateway?
An SMS gateway is the bridge between the internet and the mobile networks. Software speaks HTTP; mobile networks speak SMPP and SS7. The gateway translates between the two — it takes your request, works out which UK carrier owns the recipient's number, hands the message over in the format that carrier expects, and passes the delivery receipt back to you. Inbound messages make the same journey in reverse.
Without a gateway you would need your own SMPP binds and commercial agreements with each mobile operator. A gateway turns all of that into an account and a URL.
Live on the gateway in 3 steps
No SMPP bind to negotiate and no operator paperwork to sign.
Claim a UK number
Choose a real UK mobile, national or local number at sign-up. It is live on the gateway straight away — no provisioning queue and no operator paperwork.
Send over HTTP
Post a message from your app, a workflow tool, or the Line inbox. The gateway resolves the recipient's carrier and hands the message over for you.
Point your webhooks at it
Give Line a URL for delivery receipts and one for inbound messages. Status events arrive as the message moves through the network — no polling.
Who uses the Line UK SMS gateway? Developers, SaaS products, and growing businesses.
From one-off notifications to high-volume transactional SMS — Line scales with your product.
Transactional alerts
Order confirmations, payment receipts and appointment reminders, routed to the recipient's carrier and confirmed with a delivery receipt.
Two-factor authentication
Push one-time codes through the gateway as part of your sign-in flow. The delivery receipt confirms the code actually reached the handset.
CRM and sales tools
Trigger SMS from your CRM on deal stage changes, sign-ups or ticket updates — from code, or from no-code tools like Zapier and Make.
Developer side projects
A low-cost UK SMS gateway for your personal projects or MVPs. No enterprise contract required — pay as you go from 3p per SMS segment.
Everything your SMS gateway needs
A complete SMS API service — no third-party gateway, no enterprise contract, no hidden fees.
How Line differs from the big SMS gateways
Global gateways are built for global teams. Line is built for UK sending.
UK-first pricing
Global gateways quote per-country rates that change with the route they pick, on top of per-number and sometimes per-request fees. Line charges one flat credit rate — 3p to 4p per UK SMS segment depending on your plan, £4 a month for the number, and nothing else. No minimum monthly spend and no volume commitment to negotiate.
Dedicated UK number from day one
Large gateways often default to a shared sender ID, or make you request a UK number through a separate provisioning flow. With Line you choose a real UK mobile, national or local number at sign-up and it is live immediately.
No enterprise sales process
The large gateways are built for enterprise IT teams — a console to learn, documentation to wade through, a support queue to join. Line is self-service: sign up, pick a number, send your first SMS in under 5 minutes.
Two-way messaging built in
Global gateways treat inbound SMS as an optional add-on. Line gives you full two-way messaging — send, receive, webhook — as standard, on the same number, from the same account.
SMS gateway FAQ
How UK SMS gateways work, what they cost, and how Line routes your messages.
What is an SMS gateway?
An SMS gateway is a service that connects the internet to the mobile networks. Software speaks HTTP; mobile networks speak SMPP. The gateway translates between them — it accepts your request, identifies which UK carrier owns the recipient's number, hands the message over in the format that carrier expects, and returns the delivery receipt. Inbound messages travel the same path in reverse. Without a gateway you would need your own SMPP binds and a commercial agreement with each mobile operator.
Is there a free UK SMS gateway?
Completely free UK SMS gateways are rare and typically come with shared sender IDs, message limits, or low deliverability. Line is a low-cost UK SMS gateway rather than a free one: £4 a month for a dedicated UK number, then 3p to 4p per outbound SMS segment depending on your plan. Credits are priced at 1p each, an SMS segment costs 4 credits on Starter, 3.5 on Pro and 3 on Business, and there is no minimum spend. There is no free tier, but there is no contract either.
How does Line compare to other UK SMS gateways?
Most UK SMS gateways are either enterprise platforms that expect a contract and a sales process, or bulk senders with no inbound support. Line sits between the two: a dedicated UK number from sign-up, two-way messaging as standard, one flat credit rate rather than per-route pricing, and no minimum spend. Messages also land in a shared team inbox, so a person can pick up a conversation your software started.
Can the gateway receive SMS as well as send them?
Yes. Every Line number is two-way, so the same number that sends can receive. Configure a webhook URL in the dashboard and Line pushes each inbound message to your endpoint in real time, with the sender's number, the message body and the timestamp. Many bulk gateways treat inbound as a paid add-on or do not support it at all.
What is the difference between an SMS gateway and an SMS API?
They describe two halves of the same product. The gateway is the infrastructure — the carrier connections, the routing and the delivery receipts that get a message onto a mobile network. The API is the interface you write code against to reach that infrastructure. Line provides both: this page covers the gateway, and the SMS API page covers the endpoints, authentication and webhook payloads.
What is the throughput limit?
Standard accounts support up to 10 messages per second. Higher throughput is available on request — contact us if you need burst sending for campaigns or time-critical alerts.
Can I send from a custom sender name?
Yes, for one-way outbound-only campaigns you can use an alphanumeric sender ID (up to 11 characters). Note that alphanumeric sender IDs prevent recipients from replying. For two-way messaging, send from your dedicated UK number.
Get on a UK SMS gateway today
Pick a real UK number and send your first message in under five minutes. From £4/month — no SMPP bind, no contract, no minimum spend.
- Real UK mobile, national, or local number
- Send over HTTP or from the inbox
- Delivery receipts via webhook
- Inbound SMS webhooks included
- 3p to 4p per outbound SMS segment
- No minimum monthly spend
- No contracts — cancel anytime
- Set up in under 5 minutes
From £4/mo. Prices exclude VAT. Full pricing
Also useful: SMS API reference · SMS integrations (Zapier, Make) · OTP SMS · Virtual SMS number