The screen displays"Sim Card rejected'

The phone is probably sim locked.

If your Nokia 2310 phone displays an error message saying "Sim card Rejected" then your phone is probably network locked.To unlock it,visit the site WickedUnlock.com here they are providing the unlock code at reasonable cost with easy step by step unlocking instructions and unlock it.Then you can use freely any GSM network sim card.
http://www.wickedunlock.com/nokia-2310/rs16wp9/

what is your phone model,brand?If the phone display sim card rejected because of incorrect puk code.You can go to service provider office and get new sim card.There is another reason available for sim card rejected problem.If the phone locked to some network.It display sim card rejected when you insert another network sim card.Check which country and network it is locked now.Get unlock code from the site Unlocking4u.com for GSM network locked phones and unlocked it easily.If it is an iphone get remote unlocking service from the site and unlock it.Then use any GSM network sim card.

It's Locked to network so it displays Sim card Rejected Message.You need to Unlock it.You can get the Free Unlock code for Nokia Phones at Unlocking4free.com/nokia DCT Models and unlock it easily.

you will have to call your provider for a master un lock code

hi
you can call the company from another phone and fix the problem by giving them the PUK number.
i hope this will work

this happens when ur sim cant establish registration with the preffered networkk . this is not a phone problem . ur sim card may not hve been used for long time (recharging account) . please contact the nearest office of ur network provider

u'r sim card has been gone soo change u'r sim card

When i open my nokia 5800 it says sim card rejected what can i do helpppppppppppp

this is because ur phone is locked to a provider. you'll need to unlock your phone first and then u can use ur phone with any sim