Help! iPhone won't recognize Sim card

[tolu]

My unlocked iPhone 3g iOs 4.0.1 suddenly stoped recognizing my sim card and any other sim. It says sim failure. Don't know what 2 do. Pls pls pls help!

 

[eastercat]

Try rebooting your phone.

 

[tolu]

Re: iPhone won't recognize sim card

I tried that already, no difference!

 

[jav6454]

Simple, turn the radio off by going into "Airplane Mode". Remove SIM. Turn iPhone off. Turn iPhone on. Reinsert SIM. Turn "Airplane Mode" off.

If this fails, it's either your SIM card gone bad, hardware failure or, just restore your iPhone to that same version and re-jailbreak.

 

[mz100]

Turn airplane mode on/off
If that doesn't work...

Simply reset network settings. It will forget all of your saved wifi/VPN settings.
Settings>general>reset (all the way on bottom)>reset network settings

I have an unlocked iPhone 4 with a cut prepaid sim. And when ever it doesn't work I reset network settings and I am good to go.

Plus it only Takes a minute

 

[nmiklas21]

I have a similar problem, I have bought a locked iPhone 4 32gb from the US (I'm using it in Greece currently) in the summer, I have the 4.0 iOS, baseband 01.59.00 and jailbroken. For the last days, several times the phone gets the no service message or sim failure, I have to either switch on and off the airplane mode, or to reset network settings or to hard reset to make it get a signal. Do you know what is going on? The problem has occured only a couple of times since I got the phone but not so often as the last 2 days.
Thanks for the help!