Purched ku990 phone from e/bay

This is a normal behavior when a phone does not have a valid/working SIM card. Without a valid/working SIM card or even without a SIM card, the phone can still be used for emergency call.

I hope it helps.

Verify the sim card in another phone, probably you have a damaged sim card .

you have to unlock your phone before using it with other SIM cards, try http://www.superunlockcodes.com/ for unlocking

Try replacing you sim and if you still get the same error then it is a device issue. You will need to contact your service provider for replacement options!

You probably have the sim card in there backwards. Just got the same phone and that was why It was doing this.

Your phone is locked to ATT network. Every company does that to restrict you from getting any other network. When you insert another sim of another network, your phone gets network lock.
You have to call the current network provider to unlock you from their network. Regards, Biswa.

This phone is a POS.  Sounds like it can't read the SIM card, and therefore only 911 calls are available.

give phone a reset.....or change network settings..

I also have a x426 from 2003 and it wont work with the new ATT sim cards either, This is because of the Cingular/ATT merger which created a new network. The older original ATT phone must be unlocked to use a sim card from the new merged network. Try calling ATT Mobility customer service and request the subsidy unlock code. They are required to give it to you upon request, but it takes several days usually to get the code. I know because I used to work at a ATT call center.

I know this sounds dum but!!
does it say
insert sim
or
insert correct sim?