The £0 Travel Router in Your Drawer: What Your Old Phone Can (and Can’t) Do on a UK SIM
Most of us have one: an old phone with a cracked corner, a tired battery and no real job anymore. It sits in a drawer next to a tangle of cables, quietly losing value. But on holiday, that retired handset can earn its keep as a travel router — a little Wi-Fi bubble for your laptop, tablet and the family’s devices. Done well, it can save you from £15-a-night hotel Wi-Fi or a second data SIM. Done badly, it can hoover through your allowance before the first full English.
This isn’t about turning your old phone into a permanent router at home. It’s about the holiday use case: one UK SIM, one spare handset, several devices, and a sensible eye on cost.
Why an old phone can beat hotel Wi-Fi
Hotel Wi-Fi is a lottery. Sometimes it’s fast and free. Sometimes it’s slow, asks you to log in again every time you open the laptop, and charges extra for a second device. A spare phone with a decent data plan sidesteps all that. You set up a personal hotspot, connect your laptop and tablet, and carry on as normal.
The appeal is control. You know what the data costs because it’s your UK plan. You know the connection is yours. And you’re not faffing about with room numbers and passwords that expired yesterday.
There’s also the family angle. One spare phone can serve a tablet for the kids, a laptop for you and maybe a smart speaker if you’re that way inclined. That can be cheaper than buying a separate SIM for every device — especially on a short trip.
But there’s a catch, and it’s usually buried in the plan terms.
The tethering rule nobody reads
Tethering — also called a personal hotspot — is allowed on most UK consumer plans, but “allowed” doesn’t always mean “unlimited”. Some plans have a separate hotspot cap. Some unlimited plans slow down or stop hotspot data after a certain amount. A few value brands are stricter than the big four.
Before you pack the old phone, check your plan’s terms for the words “tethering”, “personal hotspot” or “hotspot allowance”. If you’re on a SIM-only deal with a monthly data cap, assume hotspot use counts towards it. That sounds obvious, but a laptop can eat a gigabyte in an afternoon of video calls or software updates without breaking a sweat.
If you’re on a “unlimited” plan, don’t assume the hotspot is unlimited too. In 2026, the small print still matters. Some networks advertise unlimited data for the phone but apply a fair-use or tethering limit of, say, 20GB or 30GB a month. That’s plenty for email and maps. It is not plenty for a family streaming films in a caravan.
Which UK networks are friendliest to hotspots?
As a broad rule, EE, Vodafone, Three and O2 generally permit personal hotspot use on consumer plans, but the allowances and fair-use rules vary by plan. The value brands — Smarty, Lebara, iD Mobile, Talkmobile and others — can be excellent, but check the hotspot wording before you rely on them.
Three has historically been generous with data, but its fair-use rules abroad still apply. Vodafone and EE often include roaming in Europe on eligible plans, but the hotspot allowance may be separate from the phone allowance. O2’s Europe Zone is handy, but again, read the plan details.
The safe move is simple: log into your account, find the plan terms, and search for “hotspot”. If you can’t find it, ask customer service in writing — chat is fine — and keep the reply. A screenshot of a chat saying “yes, tethering is included” is worth more than a vague memory of a sales page.
Fair use abroad: the bit that bites
Roaming fair-use rules are the second trap. Many UK plans include EU roaming, but “included” usually comes with a monthly data limit and a rule that you must mostly use the SIM in the UK. Spend too long abroad, or use too much data, and the network can apply surcharges.
Hotspot use makes this more likely because one phone can serve several devices. A laptop doing a Windows update, a tablet streaming iPlayer and a phone backing up photos can add up fast. If you’re on a 25GB EU roaming allowance, a rainy afternoon of films could take a serious bite.
The fix is boring but effective: set data limits on the spare phone, turn off automatic updates on the laptop, and download films and maps before you go. Use the hotspot for the things that need a live connection, not for everything that can wait.
Battery, heat and security
An old phone used as a hotspot gets warm. That’s normal, but don’t bury it under a pillow or leave it on a hotel windowsill in direct sun. Heat shortens battery life and can make the phone throttle the connection.
Battery is the other issue. Hotspot mode drains a phone quickly, especially if it’s also charging other devices. Bring a decent USB-C cable and a plug, and consider a small power bank for days out. If the old phone’s battery is already tired, keep it plugged in where possible.
Security matters too. Use a strong hotspot password — not “12345678” — and turn the hotspot off when you’re not using it. Don’t connect to unknown devices. If you’re using the spare phone for banking or email, keep it updated and lock it with a PIN. An old handset without security updates is fine as a router, but don’t make it your main banking phone.
The simple cost test
Before you rely on the spare-phone hotspot, do a quick sum. How much is hotel Wi-Fi? How much is a second SIM? How much data will you actually use?
If hotel Wi-Fi is £12 a night and you’re away for five nights, that’s £60. A spare phone with a 20GB hotspot allowance might cost nothing extra if it’s already on your plan. That’s a clear win. But if you need 100GB for streaming and gaming, a second local SIM or a dedicated data plan may be cheaper than the roaming charges.
The verdict
An old handset can be a genuinely useful travel router — cheap, familiar and flexible. Just don’t treat it as a magic unlimited pipe. Check your tethering allowance, watch the fair-use rules abroad, keep the phone cool and secure, and use it for the things that matter. Your drawer phone has one last job. Let it do that job without torching your data plan.
