Depending on your wireless
service provider, the Priority field might not be
available.
If you change the importance level for text messages, a high priority indicator
or low
priority indicator 
appears on your BlackBerry smartphone beside every text message that you send. If the
recipient's device model and messaging application supports importance levels for
messages, the importance level will also be indicated to the recipient.
-
On the home screen, click the Text Messages icon.
-
Press the
key >
Options.
- To set the importance level for text messages, in the SMS Text section, change the Priority field.
- To set the importance level for text messages with an attachment, in the MMS section, in the Message Filtering section, change the Importance field.
-
Press the
key >
Save.