A very strange problem has been occurring & I wish to tell you all about it. My mobile phone stopped working a couple of weeks ago. My supplier is Tesco Mobile. I have been unable to receive calls or even phone out. I have been receiving a message telling me to install Sim which of course was already installed I was advised by Tesco to try my Sim in another phone which I did & got same message. The next step was to assume my Sim had developed a fault so Tesco sent another Sim with me own number on it. I have over the last week received 4 SIM cards all showing the same fault, which shows on 3 different unlocked phones. Tesco engineers are quite baffled as both they & myself cannot fathom out what is happening. I am assuming now that ALL of Tesco stock Sims are faulty & have cancelled my contract with them. Has any other ABer experienced anything like this ? I am still at a complete loss to explain this.
Did you always try them on the same phone first? If so, there could be a fault on that phone which renders a SIM useless, so that it won't then work on any other phone.