Sprint Nextel 550 - Manual (Page 53)

Section 3: Using the PCS Connection Card
3A: The PCS Connection Manager Window and Indicators 47
Status Icons
Table 2: Status Area Icons
Icon Meaning
You are in service on the CDMA network but have no active voice or
data connection.
You have an active voice or data connection.
You missed (failed to answer) an incoming call. You can view the
number of the caller in the Call Log.
You have unread Web message(s).
You have voicemail.