BT has once again started selling mobile plans as BT Mobile after relaunching the brand it had once retired in 2023, and at first glance they are very attractively priced, with introductory offers from as little as £9 per month.

Not only that, BT Mobile also only offers 30-day rolling plans, so customers aren’t tied into lengthy months-long contracts that are difficult to get out of.

BT Mobile plans run on the EE network which is owned by parent company BT. EE was introduced as a brand in 2012 to launch the UK’s first 4G network, but BT has never abandoned its legacy BT branding.

Available with 10GB, 15GB, 30GB or 75GB mobile data per month for £9, £13, £15 or £18 per month respectively, these plans also have built-in scam protection and free EU roaming.

But if you want to take advantage of BT Mobile’s competitively priced mobile tariffs, there is a catch: you have to be a BT broadband customer, otherwise you can’t sign up at the advertised price.

“BT Mobile is exclusively available for BT Broadband customers – with double data for Halo customers,” BT said, referencing its premium-priced broadband tier, Halo.

If you still want to sign up but you don’t have BT broadband, you’ll simply have to pay more.

“BT Mobile SIM Only plans are exclusively available to BT Broadband customers,” BT said. “If you don’t have a BT Broadband plan, you will not be eligible for this exclusive price and a £5 charge will be added to the monthly cost of your plan.”

This additional £5 makes BT’s pricing much less competitive in the wider market. BT’s £9 10GB plan would be £14, £4 more than Giffgaff’s £10 tariff that gets you 20GB data.

Another thing to note is that unlike rival 30-day rolling contract plans from the likes of Giffgaff, BT Mobile plans are subject to annual price increases. BT says all its mobile plans will increase by £2.50 on March 31 each year.

That means your good deal now could get considerably more expensive as the years roll on.

If you have BT broadband and you want to simplify your billing, or can see one of the mobile plans is a better value than what you are paying now, it might make sense to switch to BT Mobile. But if you are not already a BT customer, you can likely find better value from competing SIM only mobile providers.