Mozillion review 2025: we test out the new network on EE
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We bought a SIM card from Mozillion to find out how their 5G/4G coverage, data speeds, WiFi calling and roaming compare. Last updated: 28th March 2025.
Overall rating
SIM Sherpa rates Mozillion as an ok provider
(2.5/5, ok)
"Coverage, data speeds and WiFi calling on Mozillion are identical to EE. We’re pretty sure they are just using everything off the shelf, rather than having their own systems like other operators.
We like that you can get an eSIM from them too, though it’s not an instant process. You also get EU roaming on Mozillion, which is useful. But that’s really where the added perks end.
What’s really holding Mozillion back is the customer experience once you join. You’re almost on your own. There’s no app. You can only manage a few things online, without having to call or email. Chat is a useless bot.
There’s no visibility of what you’ve used. There’s a real lack of information online too. It all feels a bit like the mobile network is an add-on to their phone buying/selling platform. Cheap plans but some work required."
The 3 best bits
1) Identical coverage / speeds to EE
2) WiFi calling and VoLTE work well
3) All plans include EU roaming
The 3 worst bits
1) No way to manage account online
2) A real lack of information
3) Feels stuck on to another business
In our Mozillion guide
Mobile network
Coverage is definitely identical to EE: and that’s good
The first thing we do when reviewing new networks is test their SIM card vs the network they piggyback on. Mozillion use the EE network completely off the shelf. We’re confident there are no differences (including band 20).
You can prove it yourself too, by checking their coverage map here. This is excellent for Mozillion customers - as it’s pretty well known that EE have the widest 4G data coverage in the country.
5G data coverage is also the best in the country. Though we would say there is plenty of 5G about on Mozillion (and other networks) that offers little speed benefit vs 4G. But more people can use it at once.
For old fashioned calls and texts via 2G (there is no 3G now on Mozillion or EE), they are beatable. If your phone has VoLTE (4G calling) this won’t be an issue though, as Mozillion support it.
Useful link: Check your local signal on Mozillion
4G/5G data speeds are the same superfast you’d hope for
The next check we do with any virtual provider like Mozillion is check their data speeds vs the network they use. Mozillion claim there are no speed caps vs EE and our own testing backs that up.
We took our SIM to known locations with high speed 4G and 5G and comfortably got over 100 Mbps. We’re confident that Mozillion’s claim of uncapped speeds is perfectly true.
That’s all good news because typical 4G speeds via EE are the fastest on average in the county. You can expect typical downloads of 45.9 Mbps according to Opensignal. That’s like decent home broadband.
5G downloads Opensignal and Speedtest estimate at 96.8 Mbps or 119.21 Mbps. That’s beatable on Three-based networks but is a sizeable upgrade on 4G. Overall, people aren’t going to be disappointed for speed.
Useful link: Data settings on Mozillion
WiFi calling and 4G calling (VoLTE) work well
Another benefit to Mozillion using everything straight from EE is that their WiFi calling and 4G calling (VoLTE) technologies are excellent. We had no issues getting the feature to kick straight in.
The call quality is very good and we were also able to switch WiFi off mid-call and transfer over to a 4G call, without it dropping. This can be a bugbear on other networks, so great to see.
4G calling is now basically essential on EE-based networks, as they have switched off traditional 3G signal. VoLTE worked perfectly straight out of the box on Mozillion.
It’s impossible for us to test compatibility on every phone model. Their support information page is also pretty limited. But we suspect the list is the same as vast EE’s one, which covers even old Android models.
Useful link: Our favourite networks for WiFi calling
You can get an eSIM but little other extra features
The main advanced network feature you get with Mozillion is that you can join on eSIM. It’s a welcome feature but theirs isn’t the slickest. It takes a while after you order for your eSIM to arrive. It’s not instant.
You’re also allowed to tether (personal hotspot) as much as you like without restrictions. Call forwarding works at device level, if you’re engaged, but not if you’re plain out of signal.
Voicemail is as you’d expect. Dial 555 and you can edit your greeting and change preferences like PINs. Mozillion don’t support the visual voicemail feature though.
There are no extras like free WiFi hotspots or free TFL WiFi. Overall, it’s not a bad set of extras. We think most people will be pretty content.
Useful link: Our guide to networks with eSIM
Extra perks and benefits
EU roaming limits are a little stingy but they do have it
We’ve not physically taken our Mozillion SIM card abroad yet. But we’re pleased to say they are one of the UK mobile networks that include EU roaming. You’ll get unlimited minutes and texts there and some data.
How much depends on your plan. 1GB users get 50% (500MB) per month, 3GB - 100GB get 25% and on their unlimited data plan, you get 25GB. If you’re away for a week or so, it should be enough.
It’s worth pointing out that Mozillion SIMs do not work if you travel outside the EU. It’s not just that it costs extra, your SIM will literally not get a connection. They just don’t have that in place.
So overall, we’d give Mozillion a middling score for roaming.
Useful link: See full ins and outs of their roaming
No credit checks or overspending
Mozillion are a little light on any other added perks. But we know that’s not really why people join networks like them. But there are few nice other things:
There is no credit check to join them, even if you join on one of their longer term contracts. This is because you buy your plan up front with them each month using a registered credit or debit card.
It also means it’s impossible to overspend, because you can only use what’s actually in your plan. That’s good if you’re handing the SIM to one of your children or just need a fixed budget.
The trade off is it’s a pain if you need to use extras, like calling a premium number, making an international call or going over data allowances. We think you can’t do this at all on Mozillion.
Useful link: Read full guide to how payment works
Prices and plans
SIM only plans from Mozillion
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Networks
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Customer experience is very basic on Mozillion
The biggest weakness of Mozillion is the customer experience once you’ve joined. Their online account management is very basic. You can change/cancel plans, turn parental controls or voicemail on/off and view payments.
But other than that, you have to contact them. You can’t see your usage history, change payment methods, buy add ons or do many simple tasks. There’s no app either. Their online chatbot is useless.
They do have a phone number you can ring. We rang it twice. First time it just rang and rang. Later, we did get through to a decent agent, who was clearly based in the UK and able to make changes to our account.
We hope this is because the SIM only side of Mozillion’s business is new. It does seem that it is something they’re working on developing, which is good news: because it’s definitely needed.
Useful link: Ways to contact Mozillion