5G Business Broadband Trial: Signal, Speed & Failover Test

A 5G logo on a router is a promise. A speed test inside your office is proof.

Plenty of UK businesses cancel their broadband, plug in a 5G SIM and find out on Monday morning that the back office gets one bar. So can 5G replace office broadband? Yes, at many UK sites it can. But only a real test at your address tells you whether yours is one of them.

This guide gives you the exact 5-day test we use with business customers. You'll learn which numbers to check, what "good" looks like and how to decide in one week.

👉 Not sure where to start? Send GleeSim your postcode and we'll check the nearest masts and suggest the strongest network for your site. Ask for a free site check →

Can 5G replace office broadband?

Yes, if your building gets a strong 5G signal and the connection passes a test with your real apps at your busiest time. A 5G business SIM in a good router can run a small office, a shop or a site cabin with no phone line. Where the signal is weak, use 5G as a backup line instead.

Think of it like this. Fibre broadband is a water pipe buried in the ground to your building. 5G is water sent through the air from a tower nearby. If the tower is close and nothing blocks it, the water flows fast. If thick walls or a hill get in the way, it slows to a trickle.

There are three ways businesses use 5G:

Setup	What it means	Best for
Primary line	5G is your only internet	Strong-signal offices, shops, sites with no fibre
Backup line	5G takes over when the broadband fails	Card machines, phones, cloud systems that can't stop
Temporary line	5G while you wait for fibre or work on a short job	New offices, pop-ups, construction sites

Waiting weeks for a fibre install? Read The Broadband Gap Nobody Warns You About.

Day 1: Read your 5G signal numbers (not the bars)

The bars on a router are a guess. The signal numbers are the truth. Every decent 4G/5G router shows them in its settings page, usually under "Mobile" or "Status". Write down these three numbers in every room where people work.

Signal number	What it means in plain English	Excellent	Good	Weak, expect trouble
RSRP (signal power)	How loud the tower sounds	Better than -80 dBm	-80 to -90 dBm	Worse than -100 dBm
RSRQ (signal quality)	How clear the voice is	Better than -10 dB	-10 to -15 dB	Worse than -20 dB
SINR (signal vs noise)	How well you hear it over the background noise	Above 20 dB	13 to 20 dB	Below 0 dB

Tip: these are minus numbers. -75 is stronger than -95, just like -2°C is warmer than -10°C.

Before you test, check the address on Ofcom's Map Your Mobile coverage checker. It shows which networks claim coverage outdoors. Then test indoors, because walls, metal roofs and coated glass can cut the signal a lot.

What to do with the results:

Move the router to a window that faces the nearest mast and test again.
Write down whether it shows 5G (NR) or has dropped to 4G (LTE).
If one network is weak, try another. GleeSim supplies SIMs on Three, O2, EE and Vodafone, plus multi-network SIMs that use the strongest one.

Day 2: Test speed, latency, jitter and packet loss

Speed is only one score. For calls and cloud apps, delay matters as much as speed.

Run a speed test 3 times a day (morning, midday, late afternoon) and record:

Test	Kid-simple meaning	Rule-of-thumb pass mark for an office
Download speed	How fast things come in	Enough for your busiest hour (measure it, see Day 3)
Upload speed	How fast things go out (video, backups, sending files)	At least 10Mbps for a small team on video calls
Latency (ping)	How long a message takes to get there and back	Under 50ms is great, under 80ms is fine
Jitter	Whether that delay keeps changing	Under 30ms
Packet loss	How many little bits of data go missing	Under 1%

Quotable line: Fast download with high jitter is like a sports car on a bumpy road. It's quick, but your Teams call still shakes.

Day 3: Test at your busiest hour

Mobile networks are shared, like a motorway. At 7am the road is empty. At 2pm, when everyone near the mast is streaming and uploading, it fills up.

Test when your office is busiest:

The Monday morning video meeting.
The afternoon when files sync to the cloud.
Any time your current broadband already struggles.

Get everyone on the trial line at once. One person browsing is not a test. Ten people on video calls is.

Not sure if unlimited data is right for your team? We've sized it for you in How Much Data Does a Business SIM Need? 20GB vs Unlimited 5G.

Day 4: Run your real business apps

A speed test is a quiz. Your apps are the real exam.

Job	Pass if…
Teams / Zoom / Google Meet	30 minutes, no frozen faces, no robot voices
VoIP phones	Callers hear you clearly, no gaps or echo
Card machine / EPOS	Payments go through first time
Cloud software (Xero, Sage, CRM)	Pages open and save without spinning
File upload	A 1GB folder uploads in the time your team expects
Remote desktop / VPN	Typing feels instant, not laggy
CCTV viewing	Live view opens from your phone off-site

Got CCTV, a VPN or anything you need to reach from outside? Most mobile SIMs (including unlimited 5G ones) use a dynamic IP behind CGNAT (carrier-grade NAT). In plain English, your router shares a public address with lots of other customers, so the outside world can't knock on its door directly. Outgoing traffic like email, Teams and cloud apps works fine. Incoming access needs a fixed (static) IP SIM. GleeSim supplies both. See Why your CCTV, POS or IoT devices need a fixed IP and the Fixed IP SIM range.

Day 5: Pull the plug (the failover test)

If 5G is your backup, test the backup before you need it. A second SIM sitting in a drawer is not a backup.

Check your router supports dual-WAN (two internet inputs) and automatic failover.
Put the 5G SIM in, set fibre as primary and 5G as secondary.
During a quiet hour, unplug the fibre cable.
Time how many seconds until the internet comes back on 5G.
Check card payments, phones and the VPN still work.
Plug the fibre back in and make sure it switches back on its own.

If it takes more than a minute, or the card machine drops, fix the settings before you rely on it. For extra resilience, a multi-network backup SIM means one network's outage doesn't take you offline.

Which router do I need for a 5G business SIM?

Use a 5G router with an unlocked SIM slot, support for UK 5G bands n78 and n28, Ethernet ports, dual-WAN failover and external antenna ports. The router matters as much as the SIM. A cheap router in a weak spot will lose to a business router by the window every time.

Check for:

5G NR (SA/NSA) support, not just 4G LTE Cat 4.
MIMO antenna ports, so you can fit an outdoor antenna if signal is weak.
Gigabit Ethernet for desks, phones and a switch.
Wi-Fi 6 if lots of devices connect.
Firmware updates and a firewall your IT person can manage.

GleeSim supplies SIMs with or without hardware. Ask us for a router matched to your site, or see industrial 5G routers for CCTV and IoT. If you'd rather not buy hardware at all, rent a pre-configured 5G router with unlimited data.

The 5G business internet scorecard

Print this. Tick it off. If you get 8 or more ticks, 5G can run your office.

RSRP better than -90 dBm where people work
SINR above 13 dB
Router shows 5G (NR), not only 4G
Upload speed at least 10Mbps at the busiest hour
Latency under 80ms, jitter under 30ms
Packet loss under 1%
30-minute video call with no freezes
Card machine and VoIP phones worked first time
Remote access works (or you've ordered a fixed IP SIM)
Failover switched in under 60 seconds
Fair-use terms checked and router use allowed
Total monthly cost (SIM + router + VAT) beats your current line

6–7 ticks: use 5G as backup, or try another network or an outdoor antenna. 5 or fewer: keep fibre as primary for now.

How much does 5G business internet cost with GleeSim?

GleeSim's unlimited 5G business SIMs start from £17 a month + VAT on a 24-month term. Shorter 12-month and 1-month rolling options are available if you want to trial first. Add the router (bought or rented) and VAT for the full monthly figure.

GleeSim unlimited plan	Network	24 months	12 months	Short term
Three Unlimited 5G Data SIM	Three	£17.00	£21.00	£24.99 (1 month)
O2 Unlimited Data SIM (650GB fair use)	O2	£19.00	£25.00	£27.00 (3 months)

Prices per month, ex VAT, from the GleeSim site in October 2026. Speeds depend on coverage, signal and network traffic. 5G needs a 5G device; the SIMs fall back to 4G where 5G isn't available.

Tip for a trial: take the shortest term first. Run the 5-day test. If it passes, move to the 24-month price and save every month.

👉 Compare unlimited 5G business SIMs →

Why UK businesses test with GleeSim

GleeSim is a boutique UK telecom company based in Livingston, Scotland, with a team that has been in telecoms since 2006. We're small enough to answer the phone and experienced enough to get it right.

We check your masts first. Send your postcode and we'll recommend the strongest network before you buy.
Every major UK network. Three, O2, EE and Vodafone, plus multi-network SIMs.
Short terms available. Trial on a 1-month or 3-month plan before you commit.
SIM only or with hardware. Routers, antennas and pre-configured rental kits.
Fixed IP when you need it. For CCTV, VPN, EPOS and remote access.
Bigger than one office? We build bespoke M2M, IoT, mobile broadband (MBB) and business mobile contracts for corporate and enterprise teams. See enterprise connectivity →

FAQ: 5G business broadband

Can 5G replace broadband for a small business?

Yes, where the building gets a strong 5G signal and passes a real-world test. Aim for RSRP better than -90 dBm, latency under 80ms and smooth video calls at your busiest hour. If it fails, use 5G as a backup line instead.

How do I test 5G signal strength in my office?

Put a 5G router with the SIM where people work and open its status page. Note RSRP, RSRQ and SINR in each room, morning and afternoon. The bars on the screen are too rough to trust.

What is a good RSRP and SINR for a 5G router?

RSRP better than -80 dBm is excellent and -80 to -90 dBm is good. SINR above 20 dB is excellent and 13–20 dB is good. Below -100 dBm RSRP or 0 dB SINR, expect drop-outs.

Is 5G good enough for Teams and Zoom calls?

Yes, when upload is at least 10Mbps, latency is under 80ms, jitter is under 30ms and packet loss is below 1%. Test with a 30-minute call while the office is busy, not first thing in the morning.

Can I use an unlimited 5G business SIM in a router?

Yes. GleeSim's unlimited data SIMs are designed for business routers and mobile broadband. Check the plan's fair-use terms (for example 650GB on the O2 Unlimited Data SIM) and that your router supports the network's 5G bands.

Is a 5G SIM good as backup broadband for business?

Yes, if your router has dual-WAN and automatic failover. Test it by unplugging the fibre and timing the switch. A multi-network SIM adds protection if one network has an outage.

Can I access CCTV or a VPN through a 5G SIM with a dynamic IP?

Usually not for incoming connections, because most mobile SIMs sit behind CGNAT. Outgoing traffic works fine. For remote access to cameras, servers or routers, use a fixed IP SIM.

5G can replace office broadband at many UK sites. It can also fail badly in the wrong room. The difference is a 5-day test, not a guess.

Read the signal numbers. Test at your busiest hour. Run your real apps. Pull the plug on failover. Then buy with proof.

Ready to run your test? Get an unlimited 5G business SIM on a short term, test it at your premises, and stay only if it passes. GleeSim checks your masts first, ships SIMs and routers, and adds fixed IP when you need it.

👉 Shop unlimited 5G business SIMs → · Get a free mast check →