Try the following actions:
- Verify that your SIM card is inserted in your BlackBerry® smartphone correctly.
- Verify that you are in a GSM® or UMTS® network area that is supported by your wireless service plan.
- Verify that the network that you want to connect to appears in your preferred wireless network list.
- On the Home screen, click the Manage Connections icon. Click Networks and Connections > Mobile Network. If the Network Technology field is set to GSM/UMTS, verify that the Network Mode field is set to one of the following: 2G & 3G or 2G & 3G/4G or 2G & 3G/H+. The options that appear in the Network Mode field depend on your wireless service provider.