Blackberry 7290 cannot find network in Bangladesh.if insert sim any card then show invalid sim card.

If your mobile shows the error message "Invalid Sim" or "Sim Rejected" the your phone is locked to a particular network. To fix this problem you need to unlock it. Use unlock code to unlock your Blackberry 7290 . To get the code you have to submit network provider, country and IMEI number of the mobile. Make sure yourself whether you have knew the network provider to which your mobile is locked, country to which the locked network belongs to and IMEI number of your mobile. If not you can find the IMEI number in two ways:
1)Go to Options>status
2)Find IMEI on the back of your mobile, behind the battery.
3)Type *#06# and press call button. It will display your IMEI number.
You can find the network provider to which your mobile is currently locked by switch off your mobile and switch on it again. A logo of the locked network will get displayed on your mobile screen. After knew all these get the code from the site Unbblock.com ,by submitting these to them. Unlock it yourself using unlocking instructions which is given in the site itself.

Your question is not clear. Is this BlackBerry a regular using one or a new one. Did you try inserting different SIM to it. Does the same message gets displayed for all the SIM.
I think your mobile must be locked to any particular network. That is why it displays invalid SIM when any new network SIM is inserted in it.
You must find out to which network has your mobile been locked to. Then get the unlock code from www.Mobileunlocksolutions.com . You need not worry about the unlocking process. You can get the complete unlocking instructions from www.Mobileunlockguide.com for free.

Either your sim card is faulty, or more likely your handset is network locked.
You will need to either purchase a new sim card (if sim is problem) or obtain the network unlock code for your phone.

Hi,

I am quite late in helping you but my information might help you in the future. If you want to unlock your blackberry, then I would recommend you Blackberry unlocking codes with IMEI. They are very reliable, CHEAPEST and provide good customer support service. Good luck!

Hi,

your phone is network locked. To unlock it you need to type MEP2 unlock code. You can buy unlock code at BlackBerry 7290 Unlock Page at FastGSM.

gsmwong

You need to get it unlocked either by doing a search for unlocking blackberry 7290 and paying one of the online services.

Service providers will unlock their phones as well just tell them your traveling abroad and you need to unlock the phone. Otherwise if it is not affiliated with a service provider you will most likely have to pay someone to get you unlock code.

Hi
That means that you need to unlock your phone, You can visit our website at www.cellunlock.net and the unlock code will be emailed to you the same day,

David
CellUnlock.net

Blackberry Technical Support team on the WEB is place to seek an answer. Or any documentation that came with the device From what you say- and I am not an expert with CellPhone devices/Systems- there appears to be no service available in your part of the world. Check out Blackberry