Insert sim card,or to view a demo of this phone first,what this means?sim is in.

You need a SIM card to make the phone work. If one is already installed it has failed or the card is not installed correctly.

Sim contacts may be dirty, either on the card or phone.
remove sim card and GENTLY rub a pencil eraser on the contacts to clean, then test. If you can access the contacts on the phone, do likewise. If not, then you'll have to use an Ether based cleaner, Like electrical parts spray ( available from your local auto parts store) .
be careful not to spray too much into the phone, as once the spray gets inside it takes longer to evaporate. You can counter the time by using compressed air to speed drying of the phone interior without taking it apart.
Hope this helps!!

My sony ericsson j20i mobile showing "insert sim card or to view the demo of this phone first view demo" at first i thought it was simlock by that network after checking with omnius for SE software it shows the phone is not locked by the network
wat does it mean? why its not detectecing pls help me
my mail id is [email protected]

you can get unlocking instructions here http://www.mobileunlockguide.com/sony-ericsson-t715a

hi, have you tried inserting another sim card? try inserting another one and if you still get the same message it means the the memory space of the phone might be faulty...if after inserting another sim and it worked properly, it means that the sim card signal is week..it means you have to contact your service provider.

Make sure the sim card is inserted in there correctly and if its still not reading the sim card it might have a Bad sim card reader

Hi

This is happening because when the Sim card is not inserted you cannot access the menu of the phone some nokia phones(including yours) are built that way.

Some nokia phones do not need a sim card for you to access the phone menu (e.g 5130,5230), while you can only view the demo of some nokia phones (e.g 1208, 1600) without a sim card

your sim might be damaged or if it is a new one sim card might not be activated by your service provider. try to insert a sim card which is working on other phones. Then you can identify the reason.

Is this a new phone? If so check that you've inserted the SIM correctly and it's not SIMlocked to another network

If it's worked before remove the SIM and GENTLY clean the contacts on the phone and the SIM with a pencil eraser.

Hey i'm having the same problem with mine, u prob got it sorted by now but i found that it is because my sim card is so old, tested it with my friends brand new sim card and works fine, 
did you solve the problem?