Android - “SIM card doesn't allow a connection to this network” ERROR I have a problem with my Xperia X10 (U20i). I purchased it new. It worked fine for a week or so, then I switched to another network operator. When I try to connect automatically it says "Registered on network" but there is no signal. I changed 3 sim cards so far. Still the same. When I put the sim card in another phone that also works, the other phone manages to find the signal. I put back the sim card in my Xperia, it works fine until for some reason I have no signal and the circle continues. I love my phone, I want it to work, with this provider.

I am very annoyed. The network provider doesn't know what could it be, they blame the phone. But the phone works with other providers with no problem so I assume it is something else.

I did a factory settings restore, I checked for updates.

I want to fix it, this issue drives me crazy and I don't want to let it go, I want to FIX it.
I think I am answering little late, but I feel my pointers might solve the issue. But still not sure.


Please check in what mode you are ? I mean are you in WCDMA only, GSM only or GSM / WCDMA preferred mode ? The best for both 3G and 2G could be GSM / WCDMA preferred mode which can switch the signal based on the 2G or 3G network. So try to change to other modes also(GSM only(For 2G only signals) or WCDMA only(For 3G only signals)).


If still no help then follow the next step.


Backup all your data to SDCard or PC and try Factory data reset. Don't do the Settings reset. Because it will do a reset of other things(Like display, Volume, etc). Factory data reset option do a reset of all the things in your phone. So make sure that all the data in your phone(Contacts, Call Log, SMS, MMS, Market Applications, etc) backed up properly.


If still no help take the phone to a nearest Sony Ericsson Customer Care center.