MPX200 SIM problem

[see23oh]

I have an MPX200 and it will not recognize the SIM card is inserted. It powers up, finds the network just fine, but loses the SIM connection either during or after calls. I have to take out the battery and reinsert the SIM in order for it to work again!. I have taken it to ATT, for assistance, they said the SIM card is fine, but gave me a new one just incase. They seem to think it is the phone. Any suggestions or thoughts on this?
Thanks

[Kris Kumar]

Sounds like it is the phone.

When you remove the SIM card, do 6 pins that make contact with the SIM card spring out. I mean do they make good contact? Is one of them loose?