The ONSIM Landline SIM is a revolutionary mobile service that allows you to run your entire business landline directly from your smartphone. Unlike traditional VoIP or "virtual" numbers, it works natively on your SIM card without the need for apps, internet data, or complex diverts.
✨ Key Features
Native Landline Caller ID: When you make an outbound call, the person you are calling sees your landline number (01, 02, 03, or 08) rather than your personal mobile number.
No Apps or VoIP: Because the service is built into the SIM itself, it uses the standard mobile voice network. This means crystal-clear call quality and no reliance on 4G/5G data or unstable WiFi.
Multiple Numbers on One SIM: You can have both a landline and a mobile number on a single SIM. You choose which one to display via your dashboard.
Professional Phone System Features: Despite being on a mobile, you get full office-grade features:
Call Transfer: Move calls to other team members.
Hunt Groups: Ring multiple phones simultaneously so a call is never missed.
Extension Numbers: Dial colleagues using short 3 or 4-digit extensions.
Call Recording: Record calls at the network level (optional add-on).
❓ How It Works
Pick a Number: Choose a new local/national landline number or port (transfer) your existing landline to ONSIM.
Install Your SIM: Choose a physical SIM or an eSIM (which activates instantly).
Start Calling: Use your phone’s normal keypad. The network automatically presents your business landline ID to the recipient.
⚖️ Landline SIM vs. Traditional VoIP Apps
| Feature | ONSIM Landline SIM | VoIP Apps (e.g., Skype/WhatsApp) |
|---|---|---|
| Call Quality | High (Standard Voice Network) | Variable (Depends on Data/WiFi) |
| Battery Life | Normal | High Drain (App must run in background) |
| User Experience | Native (Use your phone's dialler) | App-based (Must open app to call) |
| Reliability | Works even without 4G/5G data | Requires stable internet connection |
💰 Pricing & Plans
The Base Plan starts at £10/user/month (+VAT) and includes:
Unlimited UK Calls & SMS (Subject to 5,000 min / 1,000 SMS fair usage).
Choice of a new landline or using your existing one.
Flexible data bundles available as add-ons (from 2GB to 40GB).
No long-term contracts: 30 day rolling contract, cancel any time.
⚠️ Important Things to Note
SMS Messaging: While voice calls show your landline ID, SMS messages are sent from your underlying mobile number. This ensures 100% delivery reliability, as landline numbers are not designed for texting.
Marketing Use: ONSIM is for operational and person-to-person business use. Automated marketing or bulk SMS campaigns are prohibited.
Ready to set your landline free? You can order your SIM or eSIM directly at onsim.uk/landline-sim.