My new sony ericsson c 510 phone is brand new.i am used it 2 month.last week some times display inactive sim and not work phone.some time work calling the phone cut the line beep tone.display inactive sim and not work the phone?

do a master reset from the meniu of the phone

i am mobile engineer . now this time my hand sony ericsson c905 insert sim solution very need please help me

i have this too, it just turns off what ever you are doing and it claims inactive sim, then goes to demo mode. i turn it on and off and on and off multiple time to fix it it may for for 5 days or 5minutes and breaks again.

sony ericsson w350i insart sim complaint

this is happening to mine aswell. i have had it for nearly 8 months it had a good period of no problems bout 6 months after puchasing. However just today it has been saying inactive sim and re-setting itself for the last 45minutes. i blamed it on a loose sim card holder but i tightened that and it is still not working. the only way to fix this is to complain like a ***** and get your money back.

Try a new sim card made for that network.

go change the simcard

the phone needs to be diagnosed so take the phone to a mobile service center and have them correct it.

4 ur phone 2 write inactive sim is meaning dat ur old phone has been costomised with ur sim card. so use anoda sim 4 ur new phone

Sounds like a silly question but did you update the phone via the SE suite or via a flash updater? there may be problems if you left your sim in, if you flashed the phone. If you updated via the SE suite then take a look at the troubleshooting guide and moan to SE. As long as you haven't voided the warrenty on your phone there should be no problem with SE or your service provider repairing your phone for free. :)

Hope this helps. One last thing to try is to out another sim in the phone and see if it works. With any other provider except O2 you will need to use a sim the same as yours.