Your 4G router reboots overnight, the network hands it a new IP address, and by 7am your CCTV feed is unreachable, your VPN whitelist is broken, and your client is on the phone. That is the daily reality of running business-critical devices on a standard data SIM behind carrier-grade NAT (CGNAT) — and it is exactly the problem a fixed IP SIM card eliminates.

This guide covers everything UK businesses ask about static IP SIM cards in 2026: what they are, who needs one, public vs private fixed IP, prepaid vs pay monthly options, and why GleeSIM has become the agile alternative to the big static IP providers UK businesses have tolerated for years — with same-day SIM dispatch, a 24-hour turnaround on orders placed before 2:00pm on weekdays, and contracts that start at just 30 days.

👉 See GleeSIM's Fixed IP SIM plans → gleesim.co.uk/collections/fixed-ip-sim

The Problem: CGNAT, Dynamic IPs, and Why DDNS Won't Save You

Most UK mobile operators place standard data SIMs behind carrier-grade NAT (CGNAT). Your router never receives a public IP address — it shares one with thousands of other connections. The consequences for business users:

• Remote access fails. You cannot reach your 4G/5G router, CCTV cameras, or IoT devices from the outside world.
• Dynamic DNS (DDNS) does not work. DDNS needs a public IP to point at. Behind CGNAT, the IP your router reports is a private one — so the "free workaround" is a dead end.
• VPN whitelisting breaks. Corporate firewalls and payment processors that whitelist by IP reject connections every time the address rotates.
• Downtime costs real money. A construction site camera that drops offline, a payment terminal that fails PCI IP checks, a lift emergency line that can't be reached remotely — every incident is billable time, compliance risk, or safety exposure.

If you have ever searched "why can't I remote access my 4G router" or "DDNS not working on 4G", the answer is CGNAT — and the fix is a fixed IP SIM.

What Is a Fixed IP SIM Card?

A fixed IP SIM card (also called a static IP SIM) is a 4G/5G data SIM assigned a permanent, unchanging IP address — usually a static public IPv4 address. Unlike standard SIMs that receive a new dynamic IP on every connection, a fixed IP SIM keeps the same address through every reboot, network switch, and data session, enabling direct inbound remote access to routers and connected devices from anywhere in the world.

Key attributes of a fixed IP data SIM:

• Static public IPv4 address — reachable directly from the internet, with full support for port forwarding to devices on your LAN
• Private APN option — for deployments where you want a fixed private IP behind an IPsec VPN instead of public exposure
• Multi-network or single-network — non-steered multi-network SIMs connect to the strongest available signal (Vodafone, O2, Three, EE); single-network SIMs lock to one carrier
• 4G LTE and 5G ready — speeds depend on device and coverage
• All SIM form factors — triple-cut standard (2FF), micro (3FF) and nano (4FF); industrial and MFF2 embedded SIM options available for M2M deployments on request
• SIM management portal — live data usage, alerts and control across your whole SIM estate

Public vs private fixed IP: a public fixed IP lets you connect directly from any internet connection (secure it with inbound IP filtering and router firewall rules). A private fixed IP sits inside a private APN and is only reachable over a VPN tunnel — the higher-security option for corporate and critical-infrastructure use.

👉 Compare public IP and private APN options on our Fixed IP SIM collection →

Why GleeSIM Is Built Differently: Agility the Big Providers Can't Match

Most static IP SIM providers in the UK operate the same playbook: request-a-quote forms, 12–36 month minimum terms, and dispatch timelines measured in "business days". GleeSIM was built to move at the speed your project actually runs:

⚡ Same-day dispatch, 24-hour turnaround. Place your order before 2:00pm on a weekday and your fixed IP SIM ships the same day — GleeSIM's standard turnaround is 24 hours from order to SIM-in-hand for UK addresses. When a site goes live tomorrow, you cannot wait a week for provisioning.

📋 Bespoke quotes on 30-day and 90-day contracts. Need 40 SIMs for a three-month construction project? A single SIM to trial before a fleet rollout? GleeSIM provides bespoke quotes on 30-day and 90-day contract terms — something the 12/24/36-month incumbents simply do not offer. Short-term, seasonal, and project-based deployments are our home turf.

🚪 One-month cancellation notice. Once your initial committed tenure has elapsed, you can cancel with just one month's notice. No auto-rollover traps, no exit penalties, no "retention team" runaround.

📈 Scale without renegotiating. Start with one static IP SIM and grow to a hundred — same account, same portal, same pricing logic. Every SIM keeps its own dedicated static IP; nothing is drawn from a shared pool.

🇬🇧 UK-based support. GleeSIM is headquartered in Livingston, Scotland. When you call, you speak to a UK connectivity specialist — not a chatbot, not an offshore queue.

Ready to move fast? Order before 2pm and your static IP SIM ships today. Get Your Fixed IP SIM →

Frequently Asked Questions

What is a fixed IP SIM card and do I need one? A fixed IP SIM card is a mobile data SIM with a permanent, unchanging IP address. You need one if you must connect to your device remotely — CCTV viewing, router administration, VPN whitelisting, POS compliance, or IoT device management. If you only browse outward, a standard SIM is fine.

Can I use Dynamic DNS (DDNS) instead of a fixed IP SIM? No — not on modern UK 4G/5G networks. Operators use carrier-grade NAT (CGNAT), so your router never receives a public IP for DDNS to point at. A fixed IP SIM with a static public IPv4 address is the reliable solution.

What is the difference between a public and private fixed IP SIM? A public fixed IP is directly reachable from the internet — convenient for remote access, secured with firewalls and IP filtering. A private fixed IP sits inside a private APN and is only reachable via an IPsec VPN — the higher-security choice for corporate, healthcare and critical infrastructure use. GleeSIM offers both.

How fast can I get a fixed IP SIM from GleeSIM? Order before 2:00pm Monday to Friday and your SIM ships the same day — GleeSIM's standard turnaround is 24 hours to UK addresses. Configuration takes minutes once the SIM arrives.

Do fixed IP SIMs require a long contract? Not with GleeSIM. We offer bespoke quotes on 30-day and 90-day contracts, and once your initial committed term has elapsed you can cancel with just one month's notice. Most UK providers still require 12–36 month terms.

Can I get an unlimited data fixed IP SIM in the UK? Yes. GleeSIM offers unlimited 5G fixed IP SIMs on EE, Vodafone, and Three (UK & Ireland), plus an unlimited multi-network option covering the UK, Ireland and EU. Fair usage policies apply on some plans (e.g. 500GB on Three).

Will a fixed IP SIM work in my router? Yes — our triple-cut SIMs (standard 2FF, micro 3FF, nano 4FF) fit virtually every 4G/5G router, modem and gateway, including Teltonika, Robustel, Cradlepoint and Hikvision-connected devices. Industrial and MFF2 embedded formats are available for M2M projects on request.

How much does a static IP SIM card cost in the UK? GleeSIM fixed IP SIMs start at £9.50 for a 2GB multi-network plan, with unlimited 5G single-network plans from £79.99 and multi-network unlimited UK/EU coverage from £135.99. Bespoke volume pricing is available on request.