Invalid SIM on old non-smart phone

Forum|Forum|7 months ago
January 29, 2026
2 replies
51 views

EDIT: I searched and ID Mobile does not support 2g / gsm network. Writing the problem out helped me figure what to look for!

original:

I use a ID SIM card in my iPhone just fine, but when I tried it on an old Sony Ericsson T303 (released 2008) it says Invalid SIM.

Does ID mobile work on 2g network or 3G minimum?

I believe the phone is unlocked as it works with my wife’s Lebara sim (Vodafone) and the phone was originally Orange branded, now EE. And I believe if the phone was sim locked I’d be given the option of entering a code if needed.

Best answer by WelshPaul

Three UK never had a 2G network infrastructure and 3G has been discontinued.

WelshPaulAnswer

Platinum  Contributor

Three UK never had a 2G network infrastructure and 3G has been discontinued.

I have no affiliation whatsoever with iD Mobile or any subsidiary companies. Comments posted are entirely of my own opinion. Did my comment help answer your question? If so, don't forget to mark the response as the Most Helpful Answer.

Lamiya C

iD Mobile Employee

Hi @likenatureintended ,

Thank you for your message. You are correct, @WelshPaul , iD Mobile (on the Three UK network) does not support 2G/GSM, and 3G has also been discontinued. This means your older Sony Ericsson T303, which relies on 2G, will unfortunately not work with an iD Mobile SIM.

Your iPhone works because it supports 4G/VoLTE, which is fully compatible with our network.

I hope this clarifies the issue.

Lamiya

Did my comment help answer your question? If so, don't forget to mark the response as the Most Helpful Answer.