I have a Blackberry Curve 9300 having been using it for more than year. Then did a quick business trip overseas and the phone continued to function, unfortunately 24 hours upon returning to Sri Lanka, the phone refuses to accept my Dialog Sim Card which I have been using in excess of 3 years, pay as you go system. Dialog who have the Blackberry agency in Sri Lanka have been absolutely no help. The phone refuses to accept my sim card, consequently I have since purchased I new phone using same Dialog sim card....Can you help..?

If the phone does not accepts the dialog sim card then the phone must be locked to the particular network. Check the lock status of the phone, if the network lock is enabled you need to unlock the phone.

Follow the instructions given below:
1 - Switch ON your Blackberry 9300 with your current network/service provider's SIM card.
2 - Using the menu go to Settings Menu -> SIM card and press select.
3 - While holding the SHIFT key, type mepd.(NOTE: You may not see any text appear on the screen while typing mepd)
4 - You should now see the five locking categories listed.

You can get the unlock code through online, visit the site MobileUnlockSolutions.com where they are providing good service in unlocking GSM phones