Insert sim card showing

to put it again, then close your phone,wait for a moment, and then open it.It will be worked.

What is your problem with your Sim card? Is your phone shows the "No Sim" or "Insert Sim" or "Sim Rejected" or "Invalid Sim" error? If it is so i am here to help you. If your Nokia 2310 shows the "No Sim" or "Insert Sim" error then remove your Sim from your mobile and place it again correctly. Or make use of this Video to insert your Sim in your Nokia 2310. If your mobile shows the error message "Invalid Sim" or "Sim Rejected" the your phone is locked to a particular network. To fix this problem you need to unlock it. Use unlock code to unlock your Nokia 2310. To get the code you have to submit network provider, country and IMEI number of the mobile. Make sure yourself whether you have knew the network provider to which your mobile is locked, country to which the locked network belongs to and IMEI number of your mobile. If not you can find the IMEI number in two ways:
1)Go to Options>status
2)Find IMEI on the back of your mobile, behind the battery.
3)Type *#06# and press call button. It will display your IMEI number.
You can find the network provider to which your mobile is currently locked by switch off your mobile and switch on it again. A logo of the locked network will get displayed on your mobile screen. After knew all these get the code from the site Mobileunlocksolutions.com ,by submitting these to them. Unlock it yourself using unlocking instructions which is given in the site itself.

If your mobile prompts "Insert SIM" even after putting the SIM in the mobile then there must be some problem with the mobile. The mobile is not able to read the SIM. Just put a paperweight above the SIM and close. Sure it should work otherwise get a solution from a service center.

Do not worry unlocking can be done by many methods...........in that you can use the codes because its safe for your mobile..........
Get the unlocking instructions and code for your Nokia 2310 model mobile from this site Theunlockarena.com , here it can be done without any difficulty............

this can only be if the Sim card is not put correctly or the Sim card is short from inside or the Sim card slot of the phone is damaged!!try some other Sim card!

The problem could the SIM card or the phone. Remove the SIM card from the phone, insert it to another phone and try sending messages. If you can send messages then the problem lies in the phone. To verify, insert a different SIM card into your phone and try sending messages. The problem can be resolved by removing the battery and the SIM card from the phone then wait for at least 15 minutes before putting them back.

You have to openline your phone . Come to a cellphone shop and ask them to openline your phone.

sim not valid

take the phone to a mobile service center and have them check the sim holder in the phone

please service your mobile or change the sim card because problem is with your old sim cardor else the mobile you changed could be defective