Try the following actions:

• If your BlackBerry® smartphone uses a SIM card, verify that your SIM card is inserted in your smartphone correctly.
• If your smartphone normally connects to a CDMA network and your smartphone supports international roaming, verify that your smartphone is in global roaming mode and that your SIM card is inserted in your smartphone correctly.
• Verify that you turned on the connection to the wireless network.
• Verify that you're connected to your wireless service provider's network. If you switched wireless networks manually, your smartphone remains connected to that wireless network until you select your wireless service provider's network again.
• If you set a specific speed for wireless network connections, verify that you're in a wireless coverage area that supports the connection speed.