UK SMS gateway for developers
Send and receive SMS via a clean REST API. Real UK numbers, delivery receipts, inbound webhooks — everything you need to add SMS to your product today.
curl -X POST https://api.useline.io/v1/sms \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"to": "+447700900123",
"from": "+447700900456",
"body": "Hello from Line API!"
}'Delivery receipts, webhooks & UK numbers included
Try it freeFrom £1.70/mo · 1p per SMS · No contracts
Integrate in 3 steps
The fastest way to get a UK SMS gateway live in your app.
Get your API key
Sign up, choose a UK number, and your API key is available in the dashboard immediately. No sales call, no provisioning delay.
Send your first SMS
A single POST request to /v1/sms with your number, recipient, and body. Working in under 5 minutes — copy the example and paste.
Wire up webhooks
Point your delivery receipt and inbound webhook URLs at your server. Line will push real-time status events as messages move through the network.
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
Send order confirmations, payment receipts, and appointment reminders programmatically. High-throughput, delivery-guaranteed transactional SMS.
Two-factor authentication
Use the API to generate and send OTP codes as part of your authentication flow. Delivery receipts confirm the code reached the device.
CRM and sales tools
Trigger SMS from your CRM on deal stage changes, customer sign-ups, or support ticket updates — via API or no-code tools like Zapier.
Developer side projects
A low-cost UK SMS gateway for your personal projects or MVPs. No enterprise contract required — pay as you go from 1p per message.
Everything your SMS gateway needs
A complete SMS API service — no third-party gateway, no enterprise contract, no hidden fees.
Line vs Twilio and MessageBird for UK SMS
Global SMS platforms are built for global teams. Line is built for UK businesses.
UK-first pricing
Twilio charges $0.0079 per outbound UK SMS — roughly 6p. MessageBird is similar. Line charges 1p per SMS on standard plans. For UK volumes, Line is 5-6× cheaper per message, with no minimum monthly spend.
Dedicated UK number from day one
Global SMS gateways often default to shared sender IDs or require manual provisioning of a UK number. With Line, you choose a real UK mobile, national, or local number at sign-up — active immediately.
No enterprise sales process
Twilio and MessageBird are built for enterprise IT teams — complex console, long documentation, support tickets. Line is self-service: sign up, grab your API key, 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
Common questions about UK SMS gateways and the Line API.
What is an SMS gateway?
An SMS gateway is a service that translates messages from one format (typically HTTP API calls) into SMS messages delivered over mobile networks. When your app calls the Line API, the gateway routes the message to the correct UK carrier and delivers it to the recipient's handset. Inbound replies follow the same path in reverse.
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 offers a low-cost UK SMS gateway from £1.70/month for a dedicated number, with outbound SMS at 1p per message — far cheaper than Twilio or MessageBird for UK volumes. There is no free tier, but the cost is lower than most comparable services.
How does the Line SMS API compare to Twilio?
Twilio is an enterprise-grade global platform with complex pricing and a steep learning curve. Line is optimised for UK businesses: simpler API, dedicated UK numbers from the start, transparent flat pricing, and no minimum spend. For UK-only use cases, Line is typically 30–50% cheaper than Twilio at equivalent volumes.
Does the API support receiving SMS (inbound)?
Yes. Your Line number receives inbound SMS from any UK mobile. You configure a webhook URL in the dashboard and Line pushes each inbound message to your endpoint in real time. The payload includes the sender's number, message body, and timestamp.
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.
Start sending UK SMS via API today
Get a real UK number, grab your API key, and send your first message in under 5 minutes. From £1.70/month — no contracts, no minimum spend.
- Real UK mobile, national, or local number
- REST API with full documentation
- Delivery receipts via webhook
- Inbound SMS webhooks included
- 1p per outbound SMS
- No minimum monthly spend
- No contracts — cancel anytime
- Set up in under 5 minutes
From £1.70/mo. Prices exclude VAT. Full pricing
Also useful: SMS integrations (Zapier, Make) · OTP SMS · Virtual SMS number