Sim card not valid in nokia phone

Problem 1:
Your Name: lamain
Your Email Address: cavalier_lamain@yahoo.com
Subject: N73 sim card not valid
Message: my imei is 359738003088079. my phone is not start with the sim. it is saying sim card not valid.

Solve:May be its your hardware problem.What kind of SIM do you have? If you are on AT&T you should have at least one of the 3G SIMs and not the 64K or 32K SIMS.

Problem 2:
Nokia N95 - SIM card not valid?
I got Nokia N95 on ebay, when I insert AT&T 3G SIM card I get message saying "SIM card not valid". I'm not sure whats the problem... If its locked, is there any way I can know it for sure that the phone is locked?? Or what else could it be??

Solve:The N95 is locked to a particular network, depending whatever that seller was from (country) it will be locked to that country and network which the seller had it on.
If I was you I would email the seller asking which network he had it on??? If you don't get any response from the seller then go into a cell phone shop and ask them if they can help you in anyway.
Or ask them if they can unlock the phone for you it will probably cost a bit butit will be worth it so you can put you at&t sim card in it.

Problem 3:
I have an unlocked N73 that I bought unlocked from Nokia about a year ago. My first problem is that it turns on and off by itself. My second problem happened a few weeks later where I get that message "Sim Card Not Valid", I have tried rebooting and got new sim card and have no clue on what to do next. I would hate to send it to Nokia because it is out of warranty.

Solve:You can try solving the problem by updating your phone using the NSU:
Nokia Software Updater
All you need for this is a internet connection and a data cable for your phone!
Give it a try and let is know what happened!The day we stop improving is the day we stop being good.

Problem 4:
What might be the problem if my Nokia 6600 says, "SIM card not valid" even though I have unlocked it and even 'hard' formatted it?

Solve:You may just have a bad sim card.. try buying another for it